Please Whitelist This Site?

I know everyone hates ads. But please understand that I am providing premium content for free that takes hundreds of hours of time to research and write. I don't want to go to a pay-only model like some sites, but when more and more people block ads, I end up working for free. And I have a family to support, just like you. :)

If you like The TCP/IP Guide, please consider the download version. It's priced very economically and you can read all of it in a convenient format without ads.

If you want to use this site for free, I'd be grateful if you could add the site to the whitelist for Adblock. To do so, just open the Adblock menu and select "Disable on". Or go to the Tools menu and select "Adblock Plus Preferences...". Then click "Add Filter..." at the bottom, and add this string: "@@||^$document". Then just click OK.

Thanks for your understanding!

Sincerely, Charles Kozierok
Author and Publisher, The TCP/IP Guide

NOTE: Using software to mass-download the site degrades the server and is prohibited.
If you want to read The TCP/IP Guide offline, please consider licensing it. Thank you.

The Book is Here... and Now On Sale!

Get The TCP/IP Guide for your own computer.
The TCP/IP Guide

Custom Search

Table Of Contents  The TCP/IP Guide
 9  TCP/IP Application Layer Protocols, Services and Applications (OSI Layers 5, 6 and 7)
      9  Name Systems and TCP/IP Name Registration and Name Resolution
           9  TCP/IP Name Systems: Host Tables and Domain Name System (DNS)
                9  TCP/IP Domain Name System (DNS)
                     9  DNS Overview, Functions and Characteristics

Previous Topic/Section
DNS Overview, Functions and Characteristics
Previous Page
Pages in Current Topic/Section
Next Page
DNS Design Goals, Objectives and Assumptions
Next Topic/Section

DNS Overview, History and Standards
(Page 3 of 3)

DNS Evolution and Important Additional Standards

TCP/IP and the Internet have both changed a lot since 1987, of course, and DNS has also had to change to suit. Many RFCs have been written since the base documents were published in the late 1980s, most of which further clarify the operation of DNS, expand on its capabilities, or define new features for it. You can find all of these by searching for “domain” or “DNS” in a list of RFCs. There are dozens of these, and I see no point in simply listing them all here, but I have highlighted a few of the more interesting ones in Table 164.

Table 164: Additional DNS Standards

RFC Number




New DNS RR Definitions

Defines several new “experimental” resource record types. Other subsequent RFCs have also defined new RRs.


DNS Support For Load Balancing

Discusses load balancing for greater performance in DNS servers.


Incremental Zone Transfer in DNS

Specifies a new feature that allows only part of a zone to be transferred to a secondary name server for efficiency.


A Mechanism for Prompt Notification of Zone Changes (DNS NOTIFY)

Adds a new message type to DNS to allow primary (authoritative) DNS servers to tell secondary servers that information has changed in the main database.


Dynamic Updates in the Domain Name System (DNS UPDATE)

Describes a technique for dynamically making resource record changes in the DNS database (also called Dynamic DNS).


Clarifications to the DNS Specification

Discusses several issues with the main DNS standards as defined in RFCs 1034 and 1035 and how to address them.


Negative Caching of DNS Queries (DNS NCACHE)

Specifies the operation of negative caching, a feature that allows a server to maintain information about names that do not exist more efficiently.

Adapting DNS For IPv6

IP version 6 was developed starting in the mid-1990s, and brought with it the need to make changes and enhancements to the operation of DNS. (Even though DNS operates at the higher layers, it deals intimately with addresses, and addresses have changed in IPv6.) The modifications required to DNS to support IPv6 were first defined in RFC 1886, IPv6 DNS Extensions, which was part of a group of RFCs that laid out the fundamentals of IPv6. Several subsequent standards have been published since that time; these are discussed in the topic on IPv6 DNS.

The three topics following in this section provide a more complete overview of DNS and its development, by discussing the design goals of its creators, and the protocol's key characteristics.

Previous Topic/Section
DNS Overview, Functions and Characteristics
Previous Page
Pages in Current Topic/Section
Next Page
DNS Design Goals, Objectives and Assumptions
Next Topic/Section

If you find The TCP/IP Guide useful, please consider making a small Paypal donation to help the site, using one of the buttons below. You can also donate a custom amount using the far right button (not less than $1 please, or PayPal gets most/all of your money!) In lieu of a larger donation, you may wish to consider purchasing a download license of The TCP/IP Guide. Thanks for your support!
Donate $2
Donate $5
Donate $10
Donate $20
Donate $30
Donate: $

Home - Table Of Contents - Contact Us

The TCP/IP Guide (
Version 3.0 - Version Date: September 20, 2005

Copyright 2001-2005 Charles M. Kozierok. All Rights Reserved.
Not responsible for any loss resulting from the use of this site.