DDNS updates for in-addr.arpa.

[Waltner, Steve]

I've run into a problem deploying DDNS on our network related to DDNS
updates and the in-addr.arpa. domain. I've searched through the archives and
have found several discussions on using DDNS, but nothing really related to
this problem. I'm using BIND 8.2.2p7, but could move to BIND 9.0.1 if that
would help, but reading the docs on BIND 9, it might be even worse.

Current Setup:
DNS files are edited using a "updt_named" script that was developed locally.
This script creates a lock file, and than launches vi on the named.data file
for our local DNS domain (ks.lsil.com). The administrator makes their
changes to the domain serial number, and then to the actual RR data for the
domain. Once that's done, the updt_named script logs the changes that were
made, pipes the named.data file through an awk script that generates two
different in-addr.arpa zone files, HUPs the named server, wait 5 seconds,
tail the syslog messages to make sure the changes were OK, and then remove
the lock file. This has been working fine for strictly static data. All DHCP
addresses have just had an entry like "dhcp-10-0-0-1 IN A 10.0.0.1" in the
named.data file.

DDNS Problem:
The problem is you can't mix dynamic and static data in the same zone. This
is fine for the A records because I have no problem breaking the DHCP
addresses out so they are part of a dhcp.ks.lsil.com domain that would be
strictly managed by DDNS coming from the DHCP server, but there is a problem
with the PTR records in the in-addr.arpa. domain. How would you merge the
dhcp.ks.lsil.com and ks.lsil.com A records into a common list of PTR records
for the in-addr.arpa. domain? The DHCP server manages the dynamic portion of
this list, but I couldn't keep using my awk script since it wouldn't be able
to track changes that were done by the DHCP server. 

About the only thing I can think to do here would be to switch the
in-addr.arpa domain to use DDNS, and then develop a script that would look
at the changes done to the static file, and make the necessary changes to
the PTR records. That's not necessarily going to be the easiest program to
develop since the named.data file is in free text format.

I've also heard people mention packages for maintaining DNS files strictly
with DDNS updates. What are some popular programs that could do this. The
only problem I see with this is that we might loose the flexibility that we
currently have with people manually editing the named.data file. Our
named.data file is < 6000 lines, so it's still manageable in a manual
fashion. I would really miss being able to embed comments in the named.data
file if we switched to some external program to build the files for us.

--
Steve Waltner
LSI Logic
Steve.Waltner at lsil.com