Multiple DNS

bsd at bsd at
Wed Feb 22 07:05:29 PST 2006

> Le 19 févr. 06 à 08:46, Robert Slade a écrit :
>> Hi,
>> I am looking for some advice. I have a network which is based on a
>> number of servers running FreeBsd 6.0 serving Win XP work stations.
>> (yes
>> I know but..) The network is large enough to use DHCP and DNS for the
>> internal network, I have setup a DHCP server with a Dynamic DNS
>> (Bind 9)
>> on one of the servers. That server is handling the LDAP side of the
>> domain.
> Is your DNS server busy resolving internal requests or external ones ?

Mostly external from what I can ascertain, it looks like the mail server
(Qmail) doing lookups.
>> There appears to be a fair bit of DNS Traffic which leads to a
>> secondary
>> DNS being required to take some of the load as DNS lookup are slow.
>> The
>> question I have is should I just setup a cashing DNS on another server
>> using the primary as a forwarder or even several servers eg the mail
>> server and the secondary LDAP server, or should I setup a proper
>> secondary DNS using my ISP as a forwarder with dynamic updates from
>> the
>> primary.
> You should not forward anything to your ISP. This is probably the
> main reason for your DNS beeing slow.
> You should make shure you have well defined your network in your conf
> (so that you don't resolve queries for outside users...)-
> I would not advise you to forward any queries to your ISP as this
> will disable the capacity for your own server to build It's own
> resolver database and forward all the queries to the ISP (resulting
> in slow answers)!

I've now taken out the forwarders.

> Normaly you should configure the master and the slave to be
> authoritative for your internal domains.
> And configure the master and the slave to resolve ALL the Internet
> domains for your internal network and none for outside domains.
That is how I have setup the master, it only answer's queries from the
internal network.

> DNS is very tightly related to network... And we don't have any clue
> for the topology of your Net.
>> Sorry if this is a bit vague, but I have no experience in this area.
>> Rob

Thanks for the info, it has helped me. I had misunderstood the forwarders

Many thanks


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