servomapper911

Hello Everyone, Im working in the one of the biggest data centers in US as a system administrator and always have people asking me about Internet in a real live. Their big misunderstanding place is exactly about the hostname resoving, they cannot understand how IP could be attached to a hostname and thatswhy most people associate Internet with webpages, what is definately not right. I will try to explain here in short what is DNS. This will allow people to have more deep understanding about Interner. Litte bit of history: The practice of using a name as a more human-legible abstraction of a machine's numerical address on the network predates even TCP/IP, and goes all the way back to the ARPAnet era. Originally, each computer on the network retrieved a file called HOSTS.TXT from SRI (now SRI International) which mapped an address (such as 192.0.34.166) to a name (such as www.example.net.) The Hosts file still exists on most modern operating systems, either by default or through configuration, and allows users to specify an IP address to use for a hostname without checking the DNS server. This file now serves primarily for troubleshooting DNS errors or for mapping local addresses to more organic names. (The Hosts file can also help in ad-blocking, and spyware may utilize it to hijack a computer.) But a system based on a HOSTS.TXT file had inherent limitations, because of the obvious requirement that every time a given computer's address changed, every computer that wanted to communicate with it would need an update to its Hosts file. DNS in the real world Users generally do not communicate directly with a DNS resolver. Instead DNS resolution takes place transparently in client applications such as web browsers (like Internet Explorer, Opera, Mozilla Firefox, Safari, Netscape Navigator, etc), mail clients (Outlook Express, Mozilla Thunderbird, etc), and other Internet applications. When a request is made which necessitates a DNS lookup, such programs send a resolution request to the local DNS resolver in the operating system which in turn handles the communications required. The DNS resolver will almost invariably have a cache 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 a designated DNS server or 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 configure that server's address manually or allow DHCP to set it; however, where systems administrators have configured systems to use their own DNS servers, their DNS resolvers will generally point to their own nameservers. This name server will then follow the process outlined above in DNS in theory, 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. Types of DNS records Important categories of data stored in the DNS include the following: *An A record or address record maps a hostname to a 32-bit IPv4 address. * An AAAA record or IPv6 address record maps a hostname to a 128-bit IPv6 address. * A CNAME record or canonical name record makes one domain name an alias of another. The aliased domain gets all the subdomains and DNS records of the original. * An MX record or mail exchange record maps a domain name to a list of mail exchange servers for that domain. * A PTR record or pointer record maps an IPv4 address to the canonical name for that host. Setting up a PTR record for a hostname in the in-addr.arpa domain that corresponds to an IP address implements reverse DNS lookup for that address. For example (at the time of writing), www.icann.net has the IP address 192.0.34.164, but a PTR record maps 164.34.0.192.in-addr.arpa to its canonical name, referrals.icann.org. * An NS record or name server record maps a domain name to a list of DNS servers authoritative for that domain. Delegations depend on NS records. * An SOA record or start of authority record specifies the DNS server providing authoritative information about an Internet domain, the email of the domain administrator, the domain serial number, and several timers relating to refreshing the zone. * An SRV record is a generalized service location record. * A TXT record allows an administrator to insert arbitrary text into a DNS record. For example, this record is used to implement the Sender Policy Framework specification. * NAPTR records (NAPTR stands for "Naming Authority Pointer") are a newer type of DNS record that support regular expression based rewriting. Conclusion Many investigators have voiced criticism of the methods currently used to control ownership of domains. Critics commonly claim abuse by monopolies or near-monopolies, such as VeriSign, Inc. Particularly noteworthy was the VeriSign Site Finder system which redirected all unregistered .com and .net domains to a VeriSign webpage, this was rapidly removed after widespread critism. There is also significant disquiet regarding United States political influence over the Internet Corporation for Assigned Names and Numbers (ICANN). This was a significant issue in the attempt to create a .xxx Top-level domain and sparked greater interest in Alternative DNS roots that would be beyond the control of any single country. Information was combined by using different websites inluding Wikipedia. I hope this article help to understand DNS as well and assume internet is a NETWORK not a WEBPAGE. ---- Thank you for the patience. Servo.