what is a dns?

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can provide the information you are seeking.

DNS, as a computer term, refers either to the Internet?s Domain Name
System, the way terminals or servers on the network are designated, or
a Domain Name Server. To understand the second you also need to
understand the first term.

You are familiar with the usual www name followed by .com, .net, or
other designation for Web sites because that is what people normally
see either advertised, in links, or in the address bar of their
browser. This is referred to as a URL of Universal Resource Locator.

But the Internet?s routing system doesn?t identify systems by name,
rather it uses numbers in the format of four groups of digits.

For example, 127.0.0.1 is the address of your computer. That?s called
the localhost address.

The DNS is essentially a simple database or lookup table which matches
the numeric addresses with simple-to-remember text addresses. You can
have multiple text names attached to a single numeric location.

The numbering system used is at the heart of TCP/IP, or the
Transmission Control Protocol/Internet Protocol which applies to the
Web and has, in recent years, also been used for local networks. The
numbers simply tell the various machines on the Internet (or local
network) how to route the information packets sent out by your
computer and sent back to your computer from various sites you visit.

Now that you understand what the Domain Name System is, the other DNS
(Domain Name Server) is simple to explain. A DNS Server is simply one
of the many machines on the Internet which contains the database which
matches the text Web site names with the actual routing numbers needed
for the system to identify the actual system locations on the network.

The database is updated regularly and transmitted to all the DNS
Servers in the world, but not all at the same time. So, if you obtain
a URL, it may take a few days for every DNS Server in the world to
include the new Web site in their database.

You can even have a local DNS lookup table on your computer with some
addresses stored locally to save time in accessing sites you visit
regularly by skipping the use of remote DNS Servers. I won?t detail
this because you can get into some trouble if you try to do this
without understanding more about how it all works.

If you want to know the name of the server which connects you to the
Internet, just go to http://www.ipchicken.com/. This is the basic
information every Web site you contact sees about your connection. For
most people this will identify the server used by your local server
which you log onto to reach the Internet.

All Internet-related definitions (protocols) are defined in great
detail in what are known as RFCs which is short for Request For
Comments. The protocols underlying the Internet are all based on
contributions of many, many individuals who have contributed to the
RFCs.

For example, RFC 791 is the earliest basic definition of Internet
Protocol. You can see this at http://www.faqs.org/rfcs/rfc791.html.
Many RFCs are updated quite often.

Go to http://www.faqs.org/rfcs/ to see a complete list of the
standards underlying the Internet.

You can see the index of DNS RFCs at
http://www.faqs.org/cgi-bin/rfcsearch. There are scores of them, each
with many pages of technical explanations.

Another good DNS reference page is http://www.faqs.org/rfcs/dns-rfcs.html.

Google search term: dns definition
://www.google.com/search?sourceid=navclient&ie=UTF-8&rls=GGLD,GGLD:2004-43,GGLD:en&q=dns+definition

Google search term: domain name system faq
://www.google.com/search?sourceid=navclient&ie=UTF-8&rls=GGLD,GGLD:2004-43,GGLD:en&q=domain+name+system+faq

Google search term: TCP/IP
://www.google.com/search?sourceid=navclient&ie=UTF-8&rls=GGLD,GGLD:2004-43,GGLD:en&q=tcp%2Fip


For an explanation of TCP/IP
www.webopedia.com/TERM/T/TCP_IP.html
or
www.yale.edu/pclt/COMM/TCPIP.HTM 
 
Thank you again for turning to Answers.Google for help. This is a
simplified explanation of a very complex topic but I believe this
answers your question and provides a guide to locating more in depth
help if you are interested.

The Domain Name System or DNS is a system that stores information
about host names and domain names in a kind of distributed database on
networks, such as the Internet. Most importantly, it provides an IP
address for each host name, and lists the mail exchange servers
accepting e-mail for each domain.

The DNS provides a vital service on the Internet, because while
computers and network hardware work with IP addresses to perform tasks
such as addressing and routing, humans generally find it easier to
work with host names and domain names, for example in URLs and e-mail
addresses. The DNS therefore mediates between the needs and
preferences of wetware and of software.