Split horizon DNS with subnetted reverse zones

Andrew Hodgson andrew.hodgson at allpay.net
Tue Jun 21 12:27:58 UTC 2005


I am wondering whether any of you on the list can help me with a bit of a
DNS quandary I am in.

My ISP has given me an IP block  I have to host PTR records
on my DNS server using the subnetted style 208- -
this is fine.  The ISP host the zone 105.2.81.in-addr.arpa (or most of it),
and have created CNAME records pointing to the subnetted zone, listing my
public nameserver as the primary for the subnetted zone.

However, I run a split horizon DNS setup with the public information on one
server and LAN-specific information on the other.  This is mainly because
our lan uses the subdomain ad.hodgsonfamily.org.  I host the records on both
on two completely different instances.

The issue I have is I want to create the reverse zone for inside my LAN, but
here I have an issue, as if I created 105.2.81.in-addr.arpa, the rest of
that zone (i.e, for IP addresses I don't own) are not being resolved since
the DNS server can pick up the zone locally.  If I create the subnetted
zone, there would be no CNAME records in the parent to get resolution

Has anyone been in this situation before?  I have two possible workarounds,
one is to create a complete zone file for each IP address, and the other
involves ensuring only the subnetted zone exists, and relying on resolution
to find the cname records from the root nameservers, thus when it gets to
the looking up from the subnetted zone it would know the information locally
thus pick up the records?

Alternatively does anyone know a trick in bind I can use to get this working
a different (and probably more appealing!) way?


This email and any files transmitted with it are confidential and
intended solely for the use of the individual or entity to whom they
are addressed. If you have received this email in error please notify
the system manager.

allpay.net Limited, Fortis et Fides, Whitestone Business Park, Whitestone, Hereford, HR1 3SE. Telephone: 0870 243 3434, Fax: 0870 243 6041. Website: www.allpay.net Email: enquiries at allpay.net


More information about the bind-users mailing list