Jumat, 21 Oktober 2011

DNS resolvers See also: resolv.conf The client-side of the DNS is called a DNS resolver. It is responsible for initiating and sequencing the queries that ultimately lead to a full resolution (translation) of the resource sought, e.g., translation of a domain name into an IP address. A DNS query may be either a non-recursive query or a recursive query: * A non-recursive query is one in which the DNS server provides a record for a domain for which it is authoritative itself, or it provides a partial result without querying other servers. * A recursive query is one for which the DNS server will fully answer the query (or give an error) by querying other name servers as needed. DNS servers are not required to support recursive queries. The resolver, or another DNS server acting recursively on behalf of the resolver, negotiates use of recursive service using bits in the query headers. Resolving usually entails iterating through several name servers to find the needed information. However, some resolvers function more simply by communicating only with a single name server. These simple resolvers (called "stub resolvers") rely on a recursive name server to perform the work of finding information for them. [edit] Operation [edit] Address resolution mechanism Domain name resolvers determine the appropriate domain name servers responsible for the domain name in question by a sequence of queries starting with the right-most (top-level) domain label. A DNS recursor consults three nameservers to resolve the address www.wikipedia.org. The process entails: 1. A network host is configured with an initial cache (so called hints) of the known addresses of the root nameservers. Such a hint file is updated periodically by an administrator from a reliable source. 2. A query to one of the root servers to find the server authoritative for the top-level domain. 3. A query to the obtained TLD server for the address of a DNS server authoritative for the second-level domain. 4. Repetition of the previous step to process each domain name label in sequence, until the final step which returns the IP address of the host sought. The diagram illustrates this process for the host www.wikipedia.org. The mechanism in this simple form would place a large operating burden on the root servers, with every search for an address starting by querying one of them. Being as critical as they are to the overall function of the system, such heavy use would create an insurmountable bottleneck for trillions of queries placed every day. In practice caching is used in DNS servers to overcome this problem, and as a result, root nameservers actually are involved with very little of the total traffic. [edit] Circular dependencies and glue records Name servers in delegations are identified by name, rather than by IP address. This means that a resolving name server must issue another DNS request to find out the IP address of the server to which it has been referred. If the name given in the delegation is a subdomain of the domain for which the delegation is being provided, there is a circular dependency. In this case the nameserver providing the delegation must also provide one or more IP addresses for the authoritative nameserver mentioned in the delegation. This information is called glue. The delegating name server provides this glue in the form of records in the additional section of the DNS response, and provides the delegation in the answer section of the response. For example, if the authoritative name server for example.org is ns1.example.org, a computer trying to resolve www.example.org first resolves ns1.example.org. Since ns1 is contained in example.org, this requires resolving example.org first, which presents a circular dependency. To break the dependency, the nameserver for the org top level domain includes glue along with the delegation for example.org. The glue records are address records that provide IP addresses for ns1.example.org. The resolver uses one or more of these IP addresses to query one of domain's authoritative servers, which allows it to complete the DNS query. [edit] Record caching Because of the large volume of DNS requests generated for the public Internet, the designers wished to provide a mechanism to reduce the load on individual DNS servers. To this end, the DNS resolution process allows for caching of records for a period of time after an answer. This entails the local recording and subsequent consultation of the copy instead of initiating a new request upstream. The time for which a resolver caches a DNS response is determined by a value called the time to live (TTL) associated with every record. The TTL is set by the administrator of the DNS server handing out the authoritative response. The period of validity may vary from just seconds to days or even weeks. As a noteworthy consequence of this distributed and caching architecture, changes to DNS records do not propagate throughout the network immediately, but require all caches to expire and refresh after the TTL. RFC 1912 conveys basic rules for determining appropriate TTL values. Some resolvers may override TTL values, as the protocol supports caching for up to 68 years or no caching at all. Negative caching, i.e. the caching of the fact of non-existence of a record, is determined by name servers authoritative for a zone which must include the Start of Authority (SOA) record when reporting no data of the requested type exists. The value of the MINIMUM field of the SOA record and the TTL of the SOA itself is used to establish the TTL for the negative answer. [edit] Reverse lookup A reverse lookup is a query of the DNS for domain names when the IP address is known. Multiple domain names may be associated with an IP address. The DNS stores IP addresses in the form of domain names as specially formatted names in pointer (PTR) records within the infrastructure top-level domain arpa. For IPv4, the domain is in-addr.arpa. For IPv6, the reverse lookup domain is ip6.arpa. The IP address is represented as a name in reverse-ordered octet representation for IPv4, and reverse-ordered nibble representation for IPv6. When performing a reverse lookup, the DNS client converts the address into these formats, and then queries the name for a PTR record following the delegation chain as for any DNS query. For example, the IPv4 address 208.80.152.2 is represented as a DNS name as 2.152.80.208.in-addr.arpa. The DNS resolver begins by querying the root servers, which point to ARIN's servers for the 208.in-addr.arpa zone. From there the Wikimedia servers are assigned for 152.80.208.in-addr.arpa, and the PTR lookup completes by querying the wikimedia nameserver for 2.152.80.208.in-addr.arpa, which results in an authoritative response. [edit] Client lookup DNS resolution sequence Users generally do not communicate directly with a DNS resolver. Instead DNS resolution takes place transparently in applications programs such as web browsers, e-mail clients, and other Internet applications. When an application makes a request that requires a domain name lookup, such programs send a resolution request to the DNS resolver in the local operating system, which in turn handles the communications required. The DNS resolver will almost invariably have a cache (see above) containing recent lookups. If the cache can provide the answer to the request, the resolver will return the value in the cache to the program that made the request. If the cache does not contain the answer, the resolver will send the request to one or more designated DNS servers. In the case of most home users, the Internet service provider to which the machine connects will usually supply this DNS server: such a user will either have configured that server's address manually or allowed DHCP to set it; however, where systems administrators have configured systems to use their own DNS servers, their DNS resolvers point to separately maintained nameservers of the organization. In any event, the name server thus queried will follow the process outlined above, until it either successfully finds a result or does not. It then returns its results to the DNS resolver; assuming it has found a result, the resolver duly caches that result for future use, and hands the result back to the software which initiated the request. [edit] Broken resolvers An additional level of complexity emerges when resolvers violate the rules of the DNS protocol. A number of large ISPs have configured their DNS servers to violate rules (presumably to allow them to run on less-expensive hardware than a fully compliant resolver), such as by disobeying TTLs, or by indicating that a domain name does not exist just because one of its name servers does not respond.[13] As a final level of complexity, some applications (such as web-browsers) also have their own DNS cache, in order to reduce the use of the DNS resolver library itself. This practice can add extra difficulty when debugging DNS issues, as it obscures the freshness of data, and/or what data comes from which cache. These caches typically use very short caching times—on the order of one minute.[citation needed] Internet Explorer represents a notable exception: versions up to IE 3.x cache DNS records for 24 hours by default. Internet Explorer 4.x and later versions (up to IE 8) decrease the default time out value to half an hour, which may be changed in corresponding registry keys.[14] [edit] Other applications

DNS resolvers

The client-side of the DNS is called a DNS resolver. It is responsible for initiating and sequencing the queries that ultimately lead to a full resolution (translation) of the resource sought, e.g., translation of a domain name into an IP address.
A DNS query may be either a non-recursive query or a recursive query:
  • A non-recursive query is one in which the DNS server provides a record for a domain for which it is authoritative itself, or it provides a partial result without querying other servers.
  • A recursive query is one for which the DNS server will fully answer the query (or give an error) by querying other name servers as needed. DNS servers are not required to support recursive queries.
The resolver, or another DNS server acting recursively on behalf of the resolver, negotiates use of recursive service using bits in the query headers.
Resolving usually entails iterating through several name servers to find the needed information. However, some resolvers function more simply by communicating only with a single name server. These simple resolvers (called "stub resolvers") rely on a recursive name server to perform the work of finding information for them.

[edit] Operation

[edit] Address resolution mechanism

Domain name resolvers determine the appropriate domain name servers responsible for the domain name in question by a sequence of queries starting with the right-most (top-level) domain label.

A DNS recursor consults three nameservers to resolve the address www.wikipedia.org.
The process entails:
  1. A network host is configured with an initial cache (so called hints) of the known addresses of the root nameservers. Such a hint file is updated periodically by an administrator from a reliable source.
  2. A query to one of the root servers to find the server authoritative for the top-level domain.
  3. A query to the obtained TLD server for the address of a DNS server authoritative for the second-level domain.
  4. Repetition of the previous step to process each domain name label in sequence, until the final step which returns the IP address of the host sought.
The diagram illustrates this process for the host www.wikipedia.org.
The mechanism in this simple form would place a large operating burden on the root servers, with every search for an address starting by querying one of them. Being as critical as they are to the overall function of the system, such heavy use would create an insurmountable bottleneck for trillions of queries placed every day. In practice caching is used in DNS servers to overcome this problem, and as a result, root nameservers actually are involved with very little of the total traffic.

[edit] Circular dependencies and glue records

Name servers in delegations are identified by name, rather than by IP address. This means that a resolving name server must issue another DNS request to find out the IP address of the server to which it has been referred. If the name given in the delegation is a subdomain of the domain for which the delegation is being provided, there is a circular dependency. In this case the nameserver providing the delegation must also provide one or more IP addresses for the authoritative nameserver mentioned in the delegation. This information is called glue. The delegating name server provides this glue in the form of records in the additional section of the DNS response, and provides the delegation in the answer section of the response.
For example, if the authoritative name server for example.org is ns1.example.org, a computer trying to resolve www.example.org first resolves ns1.example.org. Since ns1 is contained in example.org, this requires resolving example.org first, which presents a circular dependency. To break the dependency, the nameserver for the org top level domain includes glue along with the delegation for example.org. The glue records are address records that provide IP addresses for ns1.example.org. The resolver uses one or more of these IP addresses to query one of domain's authoritative servers, which allows it to complete the DNS query.

[edit] Record caching

Because of the large volume of DNS requests generated for the public Internet, the designers wished to provide a mechanism to reduce the load on individual DNS servers. To this end, the DNS resolution process allows for caching of records for a period of time after an answer. This entails the local recording and subsequent consultation of the copy instead of initiating a new request upstream. The time for which a resolver caches a DNS response is determined by a value called the time to live (TTL) associated with every record. The TTL is set by the administrator of the DNS server handing out the authoritative response. The period of validity may vary from just seconds to days or even weeks.
As a noteworthy consequence of this distributed and caching architecture, changes to DNS records do not propagate throughout the network immediately, but require all caches to expire and refresh after the TTL. RFC 1912 conveys basic rules for determining appropriate TTL values.
Some resolvers may override TTL values, as the protocol supports caching for up to 68 years or no caching at all. Negative caching, i.e. the caching of the fact of non-existence of a record, is determined by name servers authoritative for a zone which must include the Start of Authority (SOA) record when reporting no data of the requested type exists. The value of the MINIMUM field of the SOA record and the TTL of the SOA itself is used to establish the TTL for the negative answer.

[edit] Reverse lookup

A reverse lookup is a query of the DNS for domain names when the IP address is known. Multiple domain names may be associated with an IP address. The DNS stores IP addresses in the form of domain names as specially formatted names in pointer (PTR) records within the infrastructure top-level domain arpa. For IPv4, the domain is in-addr.arpa. For IPv6, the reverse lookup domain is ip6.arpa. The IP address is represented as a name in reverse-ordered octet representation for IPv4, and reverse-ordered nibble representation for IPv6.
When performing a reverse lookup, the DNS client converts the address into these formats, and then queries the name for a PTR record following the delegation chain as for any DNS query. For example, the IPv4 address 208.80.152.2 is represented as a DNS name as 2.152.80.208.in-addr.arpa. The DNS resolver begins by querying the root servers, which point to ARIN's servers for the 208.in-addr.arpa zone. From there the Wikimedia servers are assigned for 152.80.208.in-addr.arpa, and the PTR lookup completes by querying the wikimedia nameserver for 2.152.80.208.in-addr.arpa, which results in an authoritative response.

[edit] Client lookup


DNS resolution sequence
Users generally do not communicate directly with a DNS resolver. Instead DNS resolution takes place transparently in applications programs such as web browsers, e-mail clients, and other Internet applications. When an application makes a request that requires a domain name lookup, such programs send a resolution request to the DNS resolver in the local operating system, which in turn handles the communications required.
The DNS resolver will almost invariably have a cache (see above) containing recent lookups. If the cache can provide the answer to the request, the resolver will return the value in the cache to the program that made the request. If the cache does not contain the answer, the resolver will send the request to one or more designated DNS servers. In the case of most home users, the Internet service provider to which the machine connects will usually supply this DNS server: such a user will either have configured that server's address manually or allowed DHCP to set it; however, where systems administrators have configured systems to use their own DNS servers, their DNS resolvers point to separately maintained nameservers of the organization. In any event, the name server thus queried will follow the process outlined above, until it either successfully finds a result or does not. It then returns its results to the DNS resolver; assuming it has found a result, the resolver duly caches that result for future use, and hands the result back to the software which initiated the request.

[edit] Broken resolvers

An additional level of complexity emerges when resolvers violate the rules of the DNS protocol. A number of large ISPs have configured their DNS servers to violate rules (presumably to allow them to run on less-expensive hardware than a fully compliant resolver), such as by disobeying TTLs, or by indicating that a domain name does not exist just because one of its name servers does not respond.[13]
As a final level of complexity, some applications (such as web-browsers) also have their own DNS cache, in order to reduce the use of the DNS resolver library itself. This practice can add extra difficulty when debugging DNS issues, as it obscures the freshness of data, and/or what data comes from which cache. These caches typically use very short caching times—on the order of one minute.[citation needed]
Internet Explorer represents a notable exception: versions up to IE 3.x cache DNS records for 24 hours by default. Internet Explorer 4.x and later versions (up to IE 8) decrease the default time out value to half an hour, which may be changed in corresponding registry keys.[14]

[edit] Other applications

Apa kepanjangan dari DNS ....
a. Domain Name System
b. Domain Name Service
c. Domain Network System
d. Domain Network Service
e. Domain Net System

Siapa yang menemukan DNS ....
a. David Mockapetris
b. Mchael Mockapetris
c. James Mockapetris
d. Paul Mockapetris
e. Daniel Mockapetris

Pada tahun berapa Paul Mockapetris menemukan DNS ....
a.1981
b.1982
c.1983
d.1984
e.1985

DNS adalah sebuah sistem yang menyimpan informasi tentang ....
a. nama file
b. nama jaringan
c. nama host
d. nama house
e. nama judul

Apa yang disebut sebagai server nama otoritatif yang mengasuh zona nama domain dari sebuah nama domain ....
a. Name Servers
b. Name System
c. Name Service
d. Name Susun
e. Semua benar

Jumat, 07 Oktober 2011

2.3 setting modem dial-up

Akses internet dial-up

Dari Wikipedia bahasa Indonesia, ensiklopedia bebas
Langsung ke: navigasi, cari
Dial-up connection atau dial-up saja adalah istilah teknologi informasi dalam bahasa Inggris yang mengacu kepada akses Internet dengan menggunakan jalur telepon tetap atau telepon bergerak. Pertama-tama, komputer melalui modem melakukan pemanggilan telepon (dial-up) ke Penyelenggara Jasa Internet. Setelah terhubung maka komputer dapat segera mengakses Internet dan kemudian mengakhiri koneksi dengan memutuskan hubungan telepon.
Masih banyak orang yang mempergunakan layanan Dial-up ini disebabkan ketidakmampuan mendapatkan layanan hubungan kecepatan tinggi (high-speed Internet connection), karena keterbatasan biaya dan area geografis.
Untuk melakukan Dial-up Connection, dibutuhkan perangkat-perangkat sebagai berikut:
  • Perangkat keras:
  • Perangkat Lunak: pada umumnya disediakan oleh ISP dimana kita berlangganan.
  • Nama pengguna dan kata sandi: disediakan oleh ISP dimana kita berlangganan, login tidak dapat diganti sedangkan password dapat kita ganti sendiri secara berkala untuk menjaga keamanan.
Yang perlu kita lakukan adalah:
  • Berlangganan ke salah satu ISP terdekat
  • Memasang modem ke komputer kita
  • Meng-install software Internet yang disediakan oleh ISP
  • Menghubungkan diri (dial-up) ke ISP
Setelah komputer terhubung ke ISP maka saat itu pula komputer sudah dapat terhubung ke Internet dan kita dapat memulai penjelajahan di Internet. Hubungan ke Internet hanya terjalin selama mempertahankan koneksi komputer kita ke ISP melalui modem. Begitu kita memutuskan hubungan modem ke ISP maka saat itu pula kompuer terputus dari Internet.
Hubungan yang kita lakukan ke ISP adalah hubungan lokal (menggunakan pulsa telepon lokal) namun kita sudah bisa menjelajahi Internet dan mengunjungi tempat-tempat lain di seluruh dunia. Tentunya ‘kunjungan’ kita ke tempat-tempat lain tersebut bersifat maya (tidak nyata) karena kita hanya dapat melihat-lihat informasi yang terkandung di komputer-komputer lain di seluruh dunia yang terhubung ke Internet. Karena sifatnya yang maya inilah maka Internet dikenal sebagai cyberspace (dunia maya).
Dial-up Connection ini pada umumnya digunakan oleh pribadi-pribadi yang menginginkan untuk mengakses Internet dari rumah. Komputer yang digunakan untuk dial-up pada umumnya adalah sebuah komputer tunggal (bukan jaringan komputer)
Contoh menghubungkan lewat ISP “TelkomNet Instan” 
Dalam menghubungkan diri ke Internet, ada beberapa langkah yang dilakukan oleh komputer, yaitu :
  • Dialing (memanggil nomor, misal 080989999)
  • Verifying Username (memverifikasikan nama pengguna dan sandi)
  • Handshaking ("berjabat tangan", artinya menyeragamkan parameter koneksi)
  • Connecting (menghubungkan diri ke Internet).

Senin, 03 Oktober 2011

menyimpan ,mendownloand,dan mencetak informasi dari web browser

  1. Pencarian File
3.3 Menyimpan, Mendownload, dan Mencetak Informasi dari Web Browser
A. Menyimpan Informasi
     Halamaan web yang A.berisi informasi dapat kita simpan dalam format sebagai berikut.
  1. HTML. Klik menu File---Klik Save As---Pilih direktori atau folder penyimpanan pada kotak Save in---Pada kotak Save as type, tentukan jenis penyimpanan, misalnya Web Page, complete---Ketik nama file pada kotak File Name---Klik Save
  2. Mengopi ke Ms Word. Blok teks yang dibutuhkan---Klik Menu Edit---Klik Copy---Aktifkan Ms Word---Letakkan kursor pada dokumen Word---Klik menu Edit---Klik Paste
B. Download
     Untuk melakukan download, anda dapat melakukan cara berikut.
  1. Pengambilan Gambar Bitmap dari Halaman Web. Aktifkan web browser IE---Buka halaman web yang memiliki gambar bitmap---Klik kanan pada gambar---Klik Save Picture As, kemudian akan ditampilkan kotak dialog Save Picture---Pada kotak dialog Save Picture, tentukan direktori penyimpanan, nama file, dan jenis file---Klik Save.
  2. Pembuatan Wallpaper (Background) dari Gambar Halaman Web. Aktifkan web browser IE---Buka halaman web yang memiliki gambar adatu gunakan search engine Google untuk mencari gambar---Klik kanan pada gambar halaman web---Klik Set As Background.
  3. Pengambilan Gambar Animasi Flash. Aktifkan situs yang menyediakan gambar animasi flash---Klik menu View---Klik Source---Klik menu Edit--- Klik Find---Ketik teks .swf pada kotak isian Find what---Klik tombol Find---Blok nama file dengan ekstensi swf yang ditemukan---Klik menu Edit---Klik Copy---Letakkan kursor pada Address bar halaman web yang sedang dibuka---Hapus teks URL setelah nama domain dan file flash---Klik Go atau tekan tombol Enter---Klik menu File---Klik Save As---Ganti nama file _ (garis bawah) menjadi . (titik)---Klik Save---Kemudian simpan kembali, jangan lupa ubah Save as type menjadi Web Page HTM only. Untuk membuka file animasi flash, anda harus menggunakan nama file HTML.
  4. Download File dan Informasi Melalui Situs dengan Fasilitas Download Langsung. Aktifkan situs yang menyediakan fasilitas download file---Klik file hyperlink yang dapat didownload---Kemudian akan tampil kotak konfirmasi File Download. Pilih Open untuk membuka file secara langsung dari web server, Save untuk menyimpan, atau Cancel untuk membatalkan---Pilih Save untuk menyimpannya---Tentukan folder penyimpanan pada kotak save in---Ketik nama file pada kotak file name---Klik Save---Tunggulah proses download yang sedang berlangsung.
  5. Download dengan Menu Pop-Up. Aktifkan situs yang memiliki file atau gambar yang dapat didownload---Klik kanan pada file hyperlink yang akan didownload---Klik Save Target As---Tentukan lokasi penyimpanan file---Ketik nama file pada kotak File name---Tunggulah proses download selesai.
C. Pencetakan Informasi
     Untuk mencetak informasi halaman website ke printer, lakukan langkah berikut ini.

  • Aktifkan salah satu halaman web yang akan dicetak
  • Klik Menu File
  • Klik Print
  • Pada kotak dialog Print, tentukanlah jenis printer, jumlah halaman, dan jumlah salinan.
  • Klik Print
3.4 Pendukung Web Browser dan Contoh Situs
     Kemampuan aplikasi tambahan atau pendukung disebut dengan complimentary applications atau plug-in. Fungsi dari plug-in adalah untuk meningkatkan kemampuan dari web-browser, misalnya membuka file animasi dan video. Beberapa plug-in yang umum digunakan bersama dengan web browser adalah sebagai berikut.
  1. Flash Player, aplikasi ini mendukung gambar animasi flash dan web yang dibuat dengan Macromedia Flash. Apabila komputer yang kita gunakan belum mendukung animasi flash, sebaiknya lakukan install plug-in Flash Player dengan mendownloadnya dari www.macromedia.com.
  2. Shockwave Player, aplikasi ini berguna sebagai sebuah software untuk menjalankan isi web yang dibuat dengan Macromedia Shockwave, yaitu web dengan aplikasi multimedia interaktif. Dalam web ini disajikan animasi-animasi, program demo, dan bahan-bahan presentasi.
  3. Real Player, aplikasi ini mendukung pemutaran streaming audio maupun video.
  4. Quick Time, aplikasi ini mendukung pemutaran streaming audio maupun video dengan format 3gp dan RM.
  5. Acrobat Reader, aplikasi ini berfungsi untuk membuka file dengan format PDF dan menampilkannya ke halaman web
     Beberapa mata pelajaran memiliki website tersendiri, mulai dari materi sampai evaluasinya. Berikut ini contoh dari situs-situs yang dapat membantu siswa dalam mengerjakan tugas yang diberikan guru
NYIMPAN MENDOWNLOAND DAN MENETAK INFORMQSI DARI EB BROWSER
.

tata cara akses intrnet dan localhost

Internet service provider

From Wikipedia, the free encyclopedia
An Internet service provider (ISP) is a company that provides access to the Internet. Access ISPs directly connect customers to the Internet using copper wires, wireless or fiber-optic connections.[1] Hosting ISPs lease server space for smaller businesses and host other people servers (colocation). Transit ISPs provide large tubes for connecting hosting ISPs to access ISPs.[2]

Internet connectivity options from end-user to Tier 3/2 ISPs

Contents

[hide]

[edit] History

The internet started off as a closed network between government research laboratories and relevant parts of universities. It became popular and then universities and colleges started giving more of their members access to it. As a result, commercial Internet Service Providers occurred to provide access for mainly those who missed their university accounts. In 1990, Brookline, Massachusetts-based The World became the first commercial ISP (see http://www.zakon.org/robert/internet/timeline/, also published as RFC 2235 http://tools.ietf.org/html/rfc2235).

[edit] Access ISPs

ISPs employ a range of technologies to enable consumers to connect to their network.
For users and small businesses, traditional options include: dial-up, DSL (typically Asymmetric Digital Subscriber Line, ADSL), broadband wireless, cable modem, fiber to the premises (FTTH), and Integrated Services Digital Network (ISDN) (typically basic rate interface). For customers with more demanding requirements, such as medium-to-large businesses, or other ISPs, DSL (often Single-Pair High-speed Digital Subscriber Line or ADSL), Ethernet, Metropolythian Ethernet, Gigabit Ethernet, Frame Relay, ISDN (B.R.I. or P.R.I.), ATM (Asynchronous Transfer Mode) and upload satellite Internet access. Sync-optical cabling (SONET) are more likely to be used.[citation needed]
Typical home user connectivity
Business-type connection:

[edit] Locality

When using a dial-up or ISDN connection method, the ISP cannot determine the caller's physical location to more detail than using the number transmitted using an appropriate form of Caller ID; it is entirely possible to e.g. connect to an ISP located in Mexico from the USA. Other means of connection such as cable or DSL require a fixed registered connection node, usually associated at the ISP with a physical address.

[edit] Hosting ISPs

Hosting ISPs routinely provide email, FTP, and web-hosting services. Other services include virtual machines, clouds, or entire physical servers where customers can run their own custom software.

[edit] Transit ISPs

Internet Connectivity Distribution & Core.svg
Just as their customers pay them for Internet access, ISPs themselves pay upstream ISPs for Internet access. An upstream ISP usually has a larger network than the contracting ISP and/or is able to provide the contracting ISP with access to parts of the Internet the contracting ISP by itself has no access to.
In the simplest case, a single connection is established to an upstream ISP and is used to transmit data to or from areas of the Internet beyond the home network; this mode of interconnection is often cascaded multiple times until reaching a Tier 1 carrier. In reality, the situation is often more complex. ISPs with more than one point of presence (PoP) may have separate connections to an upstream ISP at multiple PoPs, or they may be customers of multiple upstream ISPs and may have connections to each one of them at one or more point of presence.

[edit] Peering

ISPs may engage in peering, where multiple ISPs interconnect at peering points or Internet exchange points (IXs), allowing routing of data between each network, without charging one another for the data transmitted—data that would otherwise have passed through a third upstream ISP, incurring charges from the upstream ISP.
ISPs requiring no upstream and having only customers (end customers and/or peer ISPs) are called Tier 1 ISPs.
Network hardware, software and specifications, as well as the expertise of network management personnel are important in ensuring that data follows the most efficient route, and upstream connections work reliably. A tradeoff between cost and efficiency is possible.

[edit] Derivatives

The following are not a different type of the above ISPs, rather they are derivatives of the 3 core ISP types. A VISP is reselling either access or hosting services. Free ISPs are similar, but they just have a different revenue model.

[edit] Virtual ISP

A Virtual ISP (VISP) is an operation which purchases services from another ISP (sometimes called a "wholesale ISP" in this context)[3] which allow the VISP's customers to access the Internet using services and infrastructure owned and operated by the wholesale ISP.

[edit] Free ISP

Free ISPs are Internet Service Providers (ISPs) which provide service free of charge. Many free ISPs display advertisements while the user is connected; like commercial television, in a sense they are selling the users' attention to the advertiser. Other free ISPs, often called freenets, are run on a nonprofit basis, usually with volunteer staff.

[edit] Related services

[edit] See also

B.SETTING INTERNET MODE DIAL-UP

Dial-up Internet access

From Wikipedia, the free encyclopedia
Dial-up Internet access is a form of Internet access that uses the facilities of the public switched telephone network (PSTN) to establish a dialled connection to an Internet service provider (ISP) via telephone lines. The user's computer or router uses an attached modem to encode and decode Internet Protocol packets and control information into and from analogue audio frequency signals,respectively.

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[edit] Availability

Dial-up connections to the Internet require no infrastructure other than the telephone network. Where telephone access is widely available, dial-up remains useful to travellers. Dial-up is often the only choice available for rural or remote areas, where broadband installations are not prevalent due to low population density, and high infrastructure cost. Dial-up access may also be an alternative for users on limited budgets, as it is offered free by some ISPs, though broadband is increasingly available at lower prices in many countries due to market competition.
Dial-up requires time to establish a telephone connection (up to several seconds, depending on the location) and perform handshaking for protocol synchronization before data transfers can take place. In locales with telephone connection charges, each connection incurs an incremental cost. If calls are time-metered, the duration of the connection incurs costs. Dial-up access is a transient connection, because either the user, ISP or phone company terminates the connection. Internet service providers will often set a limit on connection durations to allow sharing of resources, and will disconnect the user—requiring reconnection and the costs and delays associated with it. Technically-inclined users often find a way to disable the auto-disconnect program such that they can remain connected for days.
A 2008 Pew Internet and American Life Project study states that only 10 percent of US adults still used dial-up Internet access. Reasons for retaining dial-up access include lack of infrastructure and high broadband prices.[1] This has allowed Dial-up providers such as NetZero to continue spending marketing dollars to obtain customers and commit to having U.S. based customer support.

[edit] Replacement by broadband

Broadband Internet access (cable and DSL) has been replacing dial-up access in many parts of the world. Broadband connections typically offer speeds 700 kbit/s or higher for approximately the same price as dial-up.
However, many areas still remain without high speed Internet despite the eagerness of potential customers. This can be attributed to population, location, or sometimes ISPs' lack of interest due to little chance of profitability and high costs to build the required infrastructure. Some dial-up ISPs have responded to the increased competition by lowering their rates and making dial-up an attractive option for those who merely want email access or basic web browsing.[2][3]

[edit] Recession and its effect on service

News reports in 2009 have noted a resurgence of dial-up access in the U.S. resulting from a recessionary economy, as a more affordable way of accessing the Internet.[4][5][6]
Certainly high-speed DSL and Cable are available without local phone service, but the cost of this "naked" service is noticeably higher. AT&T offers basic DSL ("Direct Express") without a phone line for $19.95/month,[7] potentially negating any savings from canceling the phone service. Cable companies do not financially penalize a subscriber for not having a local phone, however cable Internet services are usually more expensive if the customer does not subscribe to their television services.
Social networking sites such as Facebook and Twitter feature mobile editions with limited graphics and reduced functionality, designed for slow Internet connections on mobile devices. These cut-down websites will also perform well on a PC or netbook with a dial-up connection, making modern social networking possible through traditional dial-up Internet access. The affordability of dial-up Internet (and low-end PCs such as netbooks) makes this one viable option for social networking in a recessionary economy.

[edit] Performance

Modern dial-up modems typically have a maximum theoretical transfer speed of 56 kbit/s (using the V.90 or V.92 protocol), although in most cases 40–50 kbit/s is the norm. Factors such as phone line noise as well as the quality of the modem itself play a large part in determining connection speeds. Some connections may be as low as 20 kbit/s in extremely "noisy" environments, such as in a hotel room where the phone line is shared with many extensions, or in a rural area, many kilometres from the exchange. Other things such as long loops, loading coils, pair gain, electric fences (usually in rural locations), and digital loop carriers can also cripple connections to 20 kbit/s or lower.
Dial-up connections usually have latency as high as 300 ms or even more, this is longer than for many forms of broadband, such as cable or DSL, but typically less than satellite connections. Longer latency can make online gaming or video conferencing difficult, if not impossible. First person shooter style games are the most sensitive to latency, making playing them impractical on dial-up. Many modern video games do not even include the option to use dial-up. However, some games such as Everquest, Red Faction, Star Wars: Galaxies, Warcraft 3, Final Fantasy XI, Guild Wars, Unreal Tournament, Halo: Combat Evolved, Audition, Quake 3: Arena, and Ragnarok Online are capable of running on 56k dial-up.
An increasing amount of Internet content such as streaming media will not work at dial-up speeds.
Analog telephone lines are digitally switched and transported inside a Digital Signal 0 once reaching the telephone company's equipment. Digital Signal 0 is 64 kbit/s, therefore a 56 kbit/s connection is the highest that will ever be possible with analog phone lines.

[edit] Using compression to exceed 56k

The V.42, V.42bis and V.44 standards allow modems to accept uncompressed data at a rate faster than the line rate. These algorithms use data compression to achieve higher throughput.
For instance, a 53.3 kbit/s connection with V.44 can transmit up to 53.3 × 6 = 320 kbit/s if the offered data stream can be compressed that much. However, the compressibility of data tends to vary continuously, for example, due to the transfer of already-compressed files (ZIP files, JPEG images, MP3 audio, MPEG video).[8] A modem might be sending compressed files at approximately 50 kbit/s, uncompressed files at 160 kbit/s, and pure text at 320 kbit/s, or any rate in this range.[9]

[edit] Compression by the ISP

As telephone-based 56 kbit/s modems began losing popularity, some Internet Service Providers such as TurboUSA, Netzero, CdotFree, TOAST.net, and Earthlink started using pre-compression to increase the throughput and maintain their customer base. As an example, Netscape ISP uses a compression program that squeezes images, text, and other objects at a proxy server, just prior to sending them across the phone line. The server-side compression operates much more efficiently than the "on-the-fly" compression of V.44-enabled modems. Typically website text is compacted to 5% thus increasing effective throughput to approximately 1000 kbit/s, and images are lossy-compressed to 15-20% increasing throughput to about 350 kbit/s.
The drawback of this approach is a loss in quality, where the graphics acquire more compression artifacts taking on a blurry appearance; however, the perceived speed is dramatically improved and the user can manually choose to view the uncompressed images at any time. ISPs employing this approach may advertise it as "DSL speeds over regular phone lines" or simply "high speed dial-up".

[edit] List of dial-up speeds

Note that the values given are maximum values, and actual values may be slower under certain conditions (for example, noisy phone lines).[10]
Connection Bitrate

Modem 110 0.1 kbit/s
Modem 300 (Bell 103 or V.21) 0.3 kbit/s
Modem 1200 (Bell 212A or V.22) 1.2 kbit/s
Modem 2400 (V.22bis) 2.4 kbit/s
Modem 2400 (V.26bis) 2.4 kbit/s
Modem 4800 (V.27ter) 4.8 kbit/s
Modem 9600 (V.32) 9.6 kbit/s
Modem 14.4 (V.32bis) 14.4 kbit/s
Modem 28.8 (V.34) 28.8 kbit/s
Modem 33.6 (V.34) 33.6 kbit/s
Modem 56k (V.90) 56.0/33.6 kbit/s
Modem 56k (V.92) 56.0/48.0 kbit/s
Hardware compression (variable) (V.92/V.44) 56.0-320.0 kbit/s
Server-side web compression (variable) 200.0-1000.0 kbit/s

[edit] Performance assessment

Many modems were manufactured as independent communications devices connected to the computer via an RS-232 cable. Modems are capable of independently managing the connection and monitoring signal quality, and can adjust the data rate as line conditions change.
In analog serial communications modems, once the connection is established, the data communications session consumes all available bandwidth.[citation needed] Often there is no backchannel capacity for the modem to communicate connection status to the end user or local computer.[citation needed] During the connection negotiation phase, modems transmit the connection speed to the attached computer in status reports. If the base data rate changes at a later time, there is no way to indicate this change to the local computer during the data communications session.[citation needed]
Although much more capable serial communications such as USB are now used, and in approximately 1992 the soft modem was developed that uses the internal computer CPU to handle modem communications, there is still no defined industry standard backchannel method available to indicate status information such as the current base rate and actual compression ratio, to the user of the local computer.
C.SETTING KONEKSI KE ISP

CARA PENYAMBUNGAN KE INTERNET MELALUI ISP TELKOMNET 29 Oktober 2007

Posted by SIMKES UGM 2007 in internet, LAN, Teknologi Informasi.
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telkomnetAgar dapat melakukan hubungan ke internet, maka kita perlu terlebih dahulu memastikan pemasangan perangkat yang diperlukan, yaitu seperangkat komputer, modem dan jalur telepon atau kalau bagi pembaca yang telah memiliki notebook biasanya sudah include dengan modemnya, jadi notebook anda sudah siap ‘tuk dipakai. Setelah semua perangkat yang diperlukan tersedia, pengguna dapat melakukan koneksi ke ISP tempat pengguna mendaftarkan diri. Sebagi contoh, PT Telkomnet menggunakan koneksi ISP Telkomnet. ISP ini merupakan salah satu ISP yang tidak perlu mengurus pendaftaran karena fasilitas akses internet diberikan kepada tiap pelanggan PT Telkom.
Naaaah …. bagi para pembaca khususnya warga SIMKES 2007 yang ingin terus nge-net tapi koneksi gak memungkinkan atau mungkin gak ada yang gratisan alias hot spot, pake punya kantor takut dikejar dosa hi..hi.. amit-amit deh, terus yang ada cuman jalur telepon di rumah mungkin tips ini berguna dan cocok untuk dicoba. Yuppsss… ayo coba pelan-pelan dipraktekkan !telkomnet
Untuk membuat koneksi dengan ISP Telkomnet, kita perlu melakukan beberapa tahapan berikut, yaitu :
a. Langkah awal untuk membuat koneksi dengan Telkomnet, yaitu bukalah ‘Network Conection’ yang berada pada Start> Settings>Network Connections.
b. Kemudian pilihlah menu ‘Create a new connections’ pada bagian kiri atas, bila muncul tampilan “New Connection Wizard”maka tekan tombol ‘Next’
c. Kemudian kliklah ‘Connect to the Internet’, lalu tekan tombol ‘Next’
d. Selanjutnya kliklah ‘Set up my connection manually’ lalu tekan tombol ‘Next’
e. Kliklah ‘Connect using a dial-up modem’ lalu tekan tombol ‘Next’
f. Tuliskan nama ISP yang akan dihubungi, misalnya “Telkomnet”. Kemudian tekanlah tombol “Next’
g. Selanjutnya isikan nomor telepon ISP Telkomnet, yaitu 080989999. Kemudian tekanlah tombol ‘Next’
h. Langkah berikutnya adalah mengisikan user name dan password untuk Telkomnet, user name-nya adalah telkomnet@instan dan pasword-nya telkom. Selanjutnya tekanlah tombol ‘Next’
i. Tekan tombol ‘Finish’ untuk mengakhiri pembangunan koneksi ke ISP, maka akan muncul tampilan ‘dial-up’ berupa tampilan “Connect Telkomnet”
j. Untuk melakukan koneksi ke Telkomnet, tekanlah tombol ‘Dial’. Kemudian muncullah tampilan yang menunjukkan komputer sedang membangun koneksi dengan Telkomnet yaitu ditandai dengan tulisan “Connecting Telkomnet…..”
C.KONEKSI INTERNET MELALUI HANDPONE
Hape sebagai modem untuk melakukan koneksi internet merupakan cara paling sederhana yang layak dilakukan bagi generasi yang serba kebelet, misalnya sekedar untuk ber YM ria lewat pc, atau membuka email dari rekan bukan kebelet merayu cewek lho?. Tapi bagi professional surfer saya kira kurang puas, kecuali bisa melakukan tweak juga pendongrak koneksi internet.
Berikut settingan beberapa profider mulai gsm dan cdma, kalo ada yang kurang silahkan di tambahi.
Persiapan:
A.Peralatan yang di perlukan:
  1. Sebuah HP yang support GPRS, dan sudah bisa koneksi dengan GPRS.
  2. Kartu telepon / sim card.
  3. Personal computer boleh juga laptop.
  4. Perangkat koneksi, dari HP ke PC. Boleh pakai kabel data, Bluetooth, atau IrDA (Infrared Data Adapter). Berikut dengan drivernya yang sudah diinstall. Pokoknya sudah bisa kirim-kiriman antara PC dan HP.
  5. Tancapkan hanphone yang sudah aktif gprsnya (pastikan kondisi on) dengan kabel data ke usb komputer anda. Bila file driver telah ada di komputer maka secara otomatis akan mendeteksi dengan sendiri. bila tidak lakukan penginstalan driver secara manual.
B.Setting Modem
Start >> control panel >> Phone and Modem Options>> akan muncul daftar modem yang udah terdeteksi oleh komputer beserta portnya bisa com2, com7 dst. Bila sudah ada berarti terdeteksi bila belum bisa di pastikan salah satu setingan belum lengkap, periksa kabel data dan hidupkan hanphone anda.
Untuk memastikan koneksi antara pc dengan hanphone secara manual, silahkan sorot nama modem anda lalu pilih properties, di tab general akan tertera nama modem hape anda, lalau pilih diagnostics lalu query modem, bila tertera success berarti komunikasi oke.
Silahkan lihat bagian tab advanced, lalu di bagian extra setting masukkan kode dibawah ini: – lalu ok.
Kode extra setting
AT+CGDCONT=1,”IP”, “Acsess poin name operator”
Sebagai catatan: Acsess poin name merupakan variable yang senantiasa bisa berubah, kita sesuaikan dengan kartu hanphone yang kita pakai.
Contoh: anda memakai kartu im3 sebagai kartu hanphone yang anda gunakan sebagai modem handphone, maka settingannya kan jadi sebagai berikut:
AT+CGDCONT=1,”IP”,”www.indosat-im3.net”
Berikut settingan kode untuk masing masing operator:
AT+CGDCONT=1,”IP”,”www.indosat-im3.net” untuk im3
AT+CGDCONT=1,”IP”,”satelindogprs.com” untuk matrix dan mentari
AT+CGDCONT=1,”IP”,”internet” untuk telkomsel
AT+CGDCONT=1,”IP”,”xlgprs.net” untuk xl
C.Melakukan koneksi / membuat dial up:
  1. Buka Control Panel lagi,
  2. Pilih Network Connections,
  3. New Connection Wizard.
  4. Ikuti langkah-langkahnya dengan menekan Next…
  5. Untuk Connection Type, pilih Connect to the Internet
  6. Getting Ready, pilih Set up my connection manually
  7. Internet Connection, pilih Connect using a dial-up modem
  8. Pada connection name / isp name isikan nama terserah anda misal konekyuk (sebagai nama koneksi anda)
  9. Pada Phone number to dial, isikan *99***1# (lihat daftar di bawah untuk cdma berbeda)
  10. Pada dialog pengisian username dan password, sesuaikan dengan setting kartu anda. Jika menggunakan IM3, usernamenya gprs dan passwordnya im3 (lihat daftar di bawah. silahkan di sesuaikan sendiri.
  11.  D.CARA AKSES INTERNET DAN LOCALHOST

    Cara Akses Internet dan Localhost


    Internet Service Provider
    Internet Service Provider adalah suatu perusahaan yang menyediakan layanan jasa akses ke internet baik untuk personal maupun corporate, untuk computer pribadi atau dalam bentuk jaringan.
    Jenis-jenis koneksi yang diberikan oleh ISP adalah :
    1. IP connection
    Jika semua hardware dan software yang kita punya ingin secara langsung terkoneksi ke internet, maka kita harus menggunakan IP address.
    1. Dial-up connection.
    Jika kita menggunakan modem untuk dial ke ISp supaya mendapatkan koneksi ke internet, maka hal itu disebut akses dial-up.
    Berdasarkan sifatnya, ISP dibagi menjadi dua, yaitu :
    1. ISP Tertutup
    adalah ISP yang memberikan layanan akses internet hanya pada jaringan lokal
    dalam lembaga yang bersangkutan.
    1. ISP Terbuka
    Adalah ISP yang memberikan layanan akses internet untuk masyarakat luas.
    Di Indonesia ada beberapa ISP yang menyediakan layanan internet, diantaranya Indonet, Satelindo, Centrin Internet, LinkNet, telkomNet, dan sebagainya.
    · Biaya Internet
    Sistem perhitungan biaya berlangganan akses Internet ISP dibagi menjadi tiga kategori, yaitu :
    1. Volume Based
    adalah perhitunagn biaya akses Internet yang bergantung pada jumlah data yang diambil dari Internet.
    1. Time Based
    adalah perhitunagn biaya akses internet yang bergantung pada waktu yang digunakan dalam mengakses Internet.
    1. Flat Rate?Unlimited
    adalah perhitungan biaya akses Internet yang tidak bergantung kepada jumlah data yang diambil atau waktu akses Internet.
    · Layanan ISP
    ISP berkembang berdasarkan kebutuhan pengguna untuk dapet mengakses Onternet secara mudah dimanapun mereka berada.ISP berusaha memberikan layanan secara maksimal. Layana ISP tersebut adalah :
    1. Dial-up
    Adalah layanan akses Internet dengan menggunakan modem dial-up yang dihubungkan pada line telepon.
    Penggunaan akses dial-up diagi menjadi empat, yaitu :
    - Personal dial-up
    - Corporate dial-up
    - Night Server Access
    - LAN dial-up ISDN
    2. Mobile Access
    adalah layanan akses Internet melalui telepon seluler.
    3. Hotspot
    adalah layana akses Internet pada lokasi-lokasi tertentu.
    4. Wireless
    adalah layanan akses Internet tanpa kabel.
    5. Dedicated Connection
    adalah layanan akses Internet 24 jam setiap hari selama 7 hari.
    · Setting Modem Dial-UP
    Perangkat keras untuk akses Internet harus telah diinstall pada computer sebelum melakukan koneksi ke ISP. Apabila modem yang digunakan adalah modm internal, pasangkan dulu modem tersebut pada slot ekspansi yang terdapat pada mainboard. Apabila modem yang digunakan adalah modem eksternal, hubungkan terlebih dahulu kabel modem pada communication port dan aktifkan modem
    · Setting koneksi ke ISP
    Setelah perangkat yang dibutuhkan telah siap dan system operasi computer siap pula untuk digunakan.
    • Koneksi ke Internet
    Langkah-langkahnya :
    - klik menu start
    - arahkan pointer mouse pada Connet To
    - klik nama koneksi ISP ( misalnya Telkomnet@instan )
    kemudian akan tampil jendela Connect To Telkomnet@instan
    - klik Dial,tunggulah proses koneksi.
    Koneksi Internet Melalui Handphone
      1. Handphone GSM
    GPRS dapat menghubungkan anda ke Internetdimana pun berada. Dengan cara mengaktifkan layanan GPRS bersangkutan dan selanjutnya setting GPRS.
      1. Handphone CDMA
    Teknologi telepon seluler CDMA dapat digunakan akses Internet daiantaranya adalah PT Telkom dengan layanan Flexi dan Indosat dengan layanan Star One.
    Cara Akses Internet dan Localhost
    1. Perbedaan Internet dan Localhost
    Internet kepanjangan dari Interconnected Network yaitu server jaringan global yang dapat diakses oleh seluruh computer yang ada di dunia dengan kelas IP yang berbeda-beda.
    Localhost adalah server jaringan lokal yang dapat diakses oleh computer pada jaringan lokal tertentu dengan kelas IP yang sama. Untuk mengakses Internet dan localhost dilakukan dengan menggunakan bahasa protocol yang sama, yaitu HyperText Transfer protocol ( HTTP ). Web host Internet disimpan pada computer yang dapat diakses oleh seluruh computer yang terhubung jaringan Internet.
    B. Akses Internet dan Localhost
    Untuk mengakses Internet dan localhost menggunakan cara yang sama. Protokol yang digunakan adalah IP. Web browser yang digunakan adalah Internet Exploler, mozilla Firefox dan Opera.
    C. Membuat Localhost
    Membuat localhost pada computer server dimanfaatkan sebagai media pembelajaran yang interaktif. Untuk membuat localhost terdapat beberapa software yang dibutuhkan, misalnya pada system operasi Windows 2000 server dengan menggunakan Internet Information Server yang sudah terintegrasi.
    D. Membuat Virtual Host
    Modul vhost digunakan untuk membuat virtual host. Membuat virtual host pada computer lokal dapat membuat nama domain atau host sesuai keinginan.
    Jaringan rumah tipikalnya mempunyai sebuah akses stand-alone tersambung kabel misalnya melalui koneksi ....
    a. ASLD
    b. ADSL
    c. DASL
    d. LSDA
    e. DSLA

    Jaringan lokal apa yang menggunakan gelombang radio sebagai media transmisinya ....
    a. LAN Nirkabel
    b. DNS Nirkabel
    c. ISP Nirkabel
    d. Network Nirkabel
    e. DNA Nirkabel

    LAN nirkabel adalah suatu jaringan nirkabel yang menggunakan frekuensi radio untuk komunikasi antara ....
    a. perangkat lunak
    b. perangkat keras
    c. perangkat sederhana
    d. perangkat CPU
    e. perangkat komputer

    Tulang pungggung jaringan biasanya menggunakan ....
    a. Modem
    b. Telepon
    c. Kable
    d. CPU
    e. Mouse

    Sistem keamanan yang digunakan oleh WLAN awalnya adalah ....
    a. WEP
    b. WPA
    c. SSL
    d. SSH
    e. enkripsi