ARPA entries for a host with multiple IPs

[Barry Margolin]

In article <go3ka7$p4b$1 at sf1.isc.org>, shulkae <shulkae at gmail.com> 
wrote:

> Question on BIND 9 running on FreeBSD.
> 
> My customer requested to add multiple IPs to a single name so that he
> can use the round-robin feature of BIND to load-balance the service.
> 
> The entry we added looks something as below:
> 
> # more db.myzone
> ..
> ..
> ws <ip1> <ip2> <ip3>
> ..
> ..
> 
> So when my customer query the ws, he gets one of ipX any any given
> time. They never requested anything
> for updating ARPA entries for the above.
> 
> What would be the ARPA  entries for each of these? ip1, ip2 and ip3?

FYI, appropriate term would be "PTR record" or "reverse entry".  I've 
never heard them called "ARPA entries", although some call them 
"in-addrs".

> Can I add 'ws' for each of these?
> I haven't seen any references to do this either in BIND ARM or DNS/
> Bind Book.
> 
> Any tips from experienced folks?

A common practice is to create unique names for each machine, in 
addition to the round-robin entry.  This way, if you need to perform 
maintenance on a specific machine, you can go to it by its unique name.  
Then you should make the PTR record point to this name.  E.g. the 
forward zone for myzone.com would contain:

ws IN A 1.2.3.1
   IN A 1.2.3.2
   IN A 1.2.3.3

ws-1 IN A 1.2.3.1
ws-2 IN A 1.2.3.2
ws-3 IN A 1.2.3.3

and the reverse zone 3.2.1.in-addr.arpa would contain:

1 IN PTR ws-1.myzone.com.
2 IN PTR ws-2.myzone.com.
3 IN PTR ws-3.myzone.com.

-- 
Barry Margolin, barmar at alum.mit.edu
Arlington, MA
*** PLEASE don't copy me on replies, I'll read them in the group ***