DNS server issues

Tru64 5.1B PK5
I am having a weird DNS server issues. There is a reverse PRT entry I can't seem to find.  It looks like there is only be one entry (zamzam) for the IP, but there are two, and neither is what is in the named.conf file for that address. One is the hostname with two domain names attached, and the other is a name that doesn't even seem to exist there.  Here is output where i do a bunch of nslookups together, and it toggles betweem the two.
# nslookup 10.x.x.x
Server:  m.domain.com
Address:  10.x.x.1
Name:    zamzam.domain.com.domain.com
Address:  10.x.x.x
# nslookup 10.x.x.x
Server:  m.domain.com
Address:  10.x.x.1
Name:    per.domain.com
Address:  10.x.x.x
# nslookup 10.x.x.x
Server:  m.domain.com
Address:  10.x.x.1
Name:    zamzam.domain.com.domain.com
Address:  10.x.x.x
# nslookup 10.x.x.x
Server:  m.domain.com
Address:  10.x.x.1
Name:    zamzam.domain.com.domain.com
Address:  10.x.x.x
# nslookup 10.x.x.x
Server:  m.domain.com
Address:  10.x.x.1
Name:    per.domain.com
Address:  10.x.x.x
# nslookup 10.x.x.x
Server:  m.domain.com
Address:  10.x.x.1
Name:    zamzam.domain.com.domain.com
Address:  10.x.x.x
The entry in DNS looks to be zamzam.domain.com for 10.x.x.x
Thanks for the help.