Why is Splunk showing wrong hostname?

[sarashafek]

Hi,

I have a zscaler NSS connected to splunk. I've been running some tests to see how splunk reacts to change in DNS entries. 
It seems that the hostname isnt changed in splunk. Can anyone help me on this?DNS splunk 1.PNGDNS splunk 2.PNG

nssem1.clab.group is the old name.

Thanks! 

[woodcock]

Your best bet is to use the IP and then do DNS lookup at search time with:
... | lookup dnslookup clientip AS host ...

[richgalloway]

Splunk doesn't necessarily get its hostname from DNS.  It can be hardcoded in inputs.conf (host=foo) or server.conf (serverName=foo).    There's also the hostnameOption in server.conf which determines if DNS is consulted, but only applies on Windows.

[isoutamo]

It could also define so that when UF process start, it determine what is hostname at this time. Then it could be almost anything from localhost to fqdn. Actually splunk knowns hosts by GUID not by hostname.