Root Servers and Forwaders ?

Rahul Parasnis rparasnis at
Wed Mar 1 08:16:54 UTC 2000

>Rahul Parasnis wrote:
>> Hello
>> I am asking a very basic question Here?
>> In the Example described on Page 28 DNS and BIND 3rd Edition
>> Resolver query for
>> The query first goes to  "." then to "au." then "" and then to
>> "".
>> First Question : How does that First query goes to "." ?
>When the DNS server starts,  a server is chosen at random from the root
>hints. (file described on the line with "cache ." 
>This server then updates your DNS server with the current NS and glue
>records for the root servers.
>> What if I have specified "Forwarders" in my named.conf file ?
>If you do not have the record queried for, then the query will go to the
>forwarder. This is described quite well in DNS & BIND. 
>If the forwarder is unresponsive then your server will make the query to
>the internet. If slave mode (options forward only) is configured, then
>your machine will not go to the internet.
>> How does the query work , if it is given from the host
>>   where and are same level zones
>On your first query for a remote host in the .au domain, then the query
>will go to the root server who will return the NS record for the .au
>domain. Your server (or forwarder) will query the .au server and so on
>down the list. The next time you need to look for something in .au or
>one of the already cached (NS record) domains, you will go to the lowest
>level server that meets the request.  Again, read DNS & BIND for
>detailed info.
>> Second Question : What should or server have in the
>> db.cache file ?
>> Should these servers also have the file downloaded from ?
>YES.. If you can reach the internet from this machine.
And If they can't reach internet because they are not allowed, and I have
mentioned only one or two root Servers
which are the Root Servers for intranet domain then........ what should I
specify as forwarders address ?  
My confusion lies here ...
The Queried record (  is not in my cache then I will
query to the root Server .
Even if   
a. I have specified the forwarders statement ( NOT Forward only but sending
recursive query to forwarder) 
b. I have not specified the forwarder statement.

Which option is true ?

 If I have a DNS Server running on Firewall Can I specify this Server's IP
address in forwarders ( Not forward only )?
will I be able to resolv intranet as well as internet Names ? 

>> Simmilarly on Page 31 ,
>> 1.Nameserver A receives query from the resolver
>> 2. A queries B ( How this works ? Which line in the Named.conf does this?
>> does "forwarders" is doing this function ? )
>Sorry, I don't have the book handy, I  seem to have lost the need to
>read it anymore, so I don't know what page 31 says. 
>1. The resolver is the DNS client application. It goes to server A based
>on its configuration of nameserver. In Windows, this is done in the
>network control panel screen. In UNIX, it is in /etc/resolv.conf. If
>resolv.conf exists on a server and there is no nameserver directive, the
>local machine is considered to be the nameserver.
>2. I don't know what B is.
>B could be
>1. a forwarder
>2. another nameserver (root server or any subdomain.

Same question here again , Your first guess is B could be a Forwarder . 
Does it mean that when I specify following statement in my named.conf file
 forwarders {; } ;

this DNS Server will ask first a recursive query to this 'forwarder' and then 
it will query the root server specified in the hints file.
Am I right or wrong ?

- Rahul 

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