Sub domain redirection issue for umbraco

Questions
1

I have created multiple Sites at root level and setup for all sub domain to respective sites.

Issue is that any of the subdomain page is working in main domain

Example :

Main Domain : XYZ.com Sub Domain : ABC.XYZ.com/SubDomainPage

Sub domain page XYZ.com/SubDomainPage is working.

I want to restrict this link(XYZ.com/SubDomainPage) to page not found how can i do ?

I have setup the subdomain & maindomain in Culture and Hostnames. Both domain & subdomain are setup in individual sites.

We have implemeted the umbraco version 8.7.0

This is a companion discussion topic for the original entry at https://our.umbraco.com/forum/114400-sub-domain-redirection-issue-for-umbraco