An NSlookup of the ip address of hosta.ca.com was returning hostse.ca.com. This was changed to return HOSTA in capital letters
Sysview 14.2 build 960
Agent Release 10.5.0.23 (Build 990200)
With default settings, the agent is picking up the hostname, not the lpar name, unless the hostname is exactly the same as the lpar name.
The Core APM agent acquires hostname by following Java API call "InetAddress.getLocalHost.getCanonicalHostName()", where getLocalHost() returns IP, and getCanonicalHostName() queries hostname for this IP address.
It explains why duplicated DNS records for the IP address resulted in multiple host names . Also plain IP address could be returned in this erroneous case instead of hostname, if reverted lookup for IP from hostname (to prevent spoofing) fails.
It should also explain lowercase in host name (returned by DNS resolver as expected, RFC 4343), as not influenced by Java API or APM agent code