[nSLUG] DHCP/DNS client-side question

Stephen Gregory nslug at kernelpanic.ca
Sat Sep 17 20:22:58 ADT 2005

Rick Wightman wrote:

> I'm unable to determine from what tools I know how to check that the new 
> resolver settings are being transferred by DHCP to clients. Can anyone 
> help out?

On the client look in /etc/resolv.conf it will list the DNS servers that 
the client will use. On that other OS run the command ipconfig /all.

In you dhcp server config do not use the DNS servers from your provider. 
Use only your local DNS server. Configure your DNS server to use the 
ISPs servers as "forwarders." Insure that "forward only" is NOT set. 
Using this configuration your DNS server will first attempted to connect 
to your provider's servers then the root servers.

Client's aren't so smart. If configured with multiple DNS servers, some 
will use the first entry in the list for all lookups and not attempt to 
query the other servers. Other clients will use all servers in a round 
robin fashion. But if one server is down you will still experience name 
lookup failures.


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