Inverse DNS with Multiple DNS servers

Simon Waters Simon at
Tue Oct 23 03:58:04 UTC 2001

"Mark A. Bialik" wrote:
> So, just so I understand... a netblock (Class C for example) can only
> have one server provide reverse-mapping (if the whole block is
> contiguous).  But, if you subnet that baby four times (.192), you could
> ask the upstream ISP to delegate four different zones, each to a
> different DNS server on each of the four subnets?

First you don't need to "subnet" the network, to delegate a
class C in two halves. But if you have subnetted it often makes
sense for the relevant admnistrators to have the corresponding
reverse lookup delegated. This is delegation for administrative
not technical reasons, technically they could all be in the one
zone, which is also simpler to set up.

Delegation is per zone, not per server, you could and should
have multiple nameservers for each zone.

If the ISP has delegated you the whole class C, you can perform
the further delegation yourself as described in RFC2317
(Conveniently supplied in the BIND 9 source bundle, if you don't
have them otherwise to hand).

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