DNS Servers

[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.

[danielbb90]

DNS

Do Not Spam

[raintheory]

DNS

Do Not Spam

nice!

[atrain]

there's no invalid links there, it's fairly odd but wouldn't hurt some people to learn a little about it...

votes?

[jaylen]

It's like 90% Wikipedia. Seems harmless. Maybe just someone trying to spread knowledge (or has nothing better to do at work as a system admin).

[Syrius]

My doggy nose tells me it's highly suspicious. Remember that "Hi. You have a nice site. but it very hard to use!!111 *link to spam*" guy? They're just testing the waters. Exorcise it.

[danielbb90]

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.

Its spam, the smiley icon, name under there minidisc units, and there links very well hidden!

And there ate 2 more links that leads to the same page, just different urls!!!!

404: file not found ....

The page you have requested no longer exists.

This may be for a number of reasons :

* The file may have been moved or deleted by user

* The file may have been deleted for abuses

* You may have followed a link from another web site which contains an incorrect or out of date URL (Web page address)

* You may have typed an incorrect URL into your browser

* There may be an error on the site

If you think there is an error, please let us know by sending an e-mail to problems@stuphome.com

Please quote this information :

Referring page : http://domain1.com/referer_page.html

Requested page : http://domain2.com/target_page.html

Apache/2.2.3 (Unix) mod_ssl/2.2.3 OpenSSL/0.9.7g

3 Spam links in there. WELL HIDDEN

Edited August 27, 2006 by danielbb90

[atrain]

thanks for the detective work guys, all the links i moused over were valid wiki links.

topic will be left often for historical purposes cause you guys are all rad & the links are crap anyway...

[jaylen]

name under there minidisc units

I noticed that, too, and that's usually spam's warning shot for me. If spam were a disease, this guy/girl may be just a papercut. Besides, the post is so long (and boring, for me, at least), that I can't see an MDCF-er taking the time to read it and clicking away. If it gets worse, I'm sure Adrian et al have their fingers on the trigger already.

It sure beats the spam about weight loss, drug discounts, cell phone sales, and odd fetishes involving minors and barnyard animals.

[danielbb90]

It sure beats the spam about weight loss, drug discounts, cell phone sales, and odd fetishes involving minors and barnyard animals.

Yeh tell me about it

One day spam will be defeted and in that day the world wil die!

Well it probably won't happen but it would be neat.