SixFive7,
There is a lot of confusion regarding DNS and NameServers as both terms can be used interchangeably.
They are basically the same, but the naming (DNS or NameServer) helps us distinguish the role they play.
We use the term "DNS server" when the server contains all the information about the domain or when it is the first point of contact for everyone (the Internet) trying to obtain information about the domain.
If the domain is a complex one, containing multiple DNS servers, the other DNS servers are refered to as NameServers, indicating that they contain information that is specific for that part of the domain.
To explain, I'll use a small example.
Every active domain requires a DNS server.
Each DNS server contains information about that particular domain. This information includes, mail server, canonical names (aliases - e.g www) and most importantly the domains 2 Name Servers (primary and secondary).
When a domain has a simple structure, like Firewall.cx's, then the DNS server in charge for the domain will also act as a NameServer for it, containing ALL information about the domain.
On the other hand, if the domain is quite complex, meaning it has subdomains, then the DNS server will most probably not contain all information for that domain, but a part of it. So it will be a name server for part of the domain.
Let's take a look at Microsoft.com.
[code:1]
Microsoft.com (Top Level)(*)
| (ns1, ns2)
|
/ \
/ \
/ \
/ \
(**)Support.Microsoft.com Finance.Microsoft.com(***)
(ns1, ns2) (ns1,ns2)
*=Zone 1 - Microsoft.com
**=Zone 2 - support.microsoft.com
***=Zone 3 - finance.microsoft.com
[/code:1]
As you can see, in this example, microsoft's domain is split into 3 different partitions (the proper term is
zone)
Each zone has its own Name Server(s) that contain information about it. This also helps distribute the load and also make it easier to manage.
Zone 1, the top level of the domain microsoft.com will have these mappings (I've used random IP's for illustrative purposes):
~~~~~~~~~~~~~~~~~~~~~~~~~~~
Primary NameServer for microsoft.com=10.0.0.1
Secondary NameServer for microsoft.com=10.0.0.2
Primary NameServer for support.microsoft.com=15.0.0.1
Secondary NameServer for support.microsoft.com=15.0.0.2
Primary NameServer for finance.microsoft.com=20.0.0.1
Secondary NameServer for finance.microsoft.com=20.0.0.2
~~~~~~~~~~~~~~~~~~~~~~~~~~~
From there on, each Zone's name server(s) will contain further information like www,ftp, mail or what ever else they might have.
This way, if you typed "
www.support.microsoft.com
" your query will firstly go to the .Microsoft.com DNS server, (either ns1.microsoft.com or ns2.microsoft.com).
The DNS server will figure out you are referring to a zone within the domain that it doesn’t have much information about, and will then do one of the two following:
1) Contact the support.microsoft.com nameserver with your query and return the answer to you (this is called a recursive query)
or
2) The microsoft.com DNS server will tell you to go get it yourself by providing you the nameserver in charge of the support.microsoft.com zone (in this case, ns1 or ns2 .support.microsoft.com). (non-recursive query)
Your PC will then automatically ask the nameserver that was provided to it, which will then respond with the answer!
Confused ?
If yes, I wouldn't blame you. I'd suggest you read the DNS section covered on the site and then come back here and read my reply!
