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what is DNS?

Posted on 2009-04-01
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what is DNS?
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Question by:YRich
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The Domain Name System (abbreviated DNS) is an Internet directory service. DNS is how domain names are translated into IP addresses, and DNS also controls email delivery. If your computer cannot access DNS, your web browser will not be able to find web sites, and you will not be able to receive or send email.

The DNS system consists of three components: DNS data (called resource records), servers (called name servers), and Internet protocols for fetching data from the servers.

The billions of resource records in the DNS are split into millions of files called zones. Zones are kept on authoritative servers distributed all over the Internet, which answer queries based on the resource records stored in the zones they have copies of. Caching servers ask other servers for information and cache any replies. Most name servers are authoritative for some zones and perform a caching function for all other DNS information. Large name servers are often authoritative for tens of thousands of zones, but most name servers are authoritative for just a few zones.
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by:JFrederick29
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Hostname to IP Address mapping.

www.google.com = 74.125.93.147

http://en.wikipedia.org/wiki/Domain_Name_System
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by:computerfixins
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Simpler terms:

Yellow pages for the internet. :)
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by:Geisrud
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Like the other gents said, it allows you to use more user-friendly names to get to a website, like when you type www.experts-exchange.com into your web browser of choice.

Your computer then communicates with other computers and learns that, as far as the Internet is concerned, www.experts-exchange.com is the same as 64.156.132.140 (which you can also type into your web browser!).
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by:PCBONEZ
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In English... LOL
It's basically a Noun to Digital name converter service.

An IP address looks like: 64.156.132.140
It is 'like' a phone number to a computer or to a networking device. [Like a Router.]
Using TCP/IP computers actually connect and communicate using IP Addresses.

DNS is basically 'a library' function that keeps a record of the noun names humans assign to devices at various IP addresses.

~~~
Lets assume your LAN has a PC 'Named' "HIS" and another named "HERS"
The IP for "HIS" is 88.88.88.88
The IP for "HERS" is 44.44.44.44
[These numbers are totally bogus by the way.]
~~~

If you are on HIS and you want a file on HERS then having DNS enables you to type in "HERS" to get to the file instead of typing in "44.44.44.44".
.
Some computer(s) (or some Routers and Switches can do it) on you network need(s) to be designated as the DNS Server and have that Service enabled. That's the device where the library records are PHYSICALLY stored. When you type in "HERS" your PC asks the DNS Server what the IP Address is for HERS and it connects to HERS using the IP Address.
If that/those device(s) is/are off you may have problems accessing other computers.
.
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