How to change splunk search hed deafult hostname with some DNS?

[ajitshukla61116]

I have hostname tb1239905 and port 18000 ,I want to access my with test.splunk.in.
When ever splunk send mail link ,It should include this hostname test.splunk.in not the default one.

Its very urgent please help me.

[starcher]

https://docs.splunk.com/Documentation/Splunk/7.3.0/Admin/Changedefaultvalues