Hi @chintan97patel
There is a servlet registered on selector "childrenlist" by WCM Core bundle. This servlet is only called if the path is called with childrenlist as the first selector thats why yours calls like https://www.example.com/sdfsdf.childrenlist.html, https://www.example.com/sdfsdf.childrenlist.sdfsdf.html are giving response and others are throwing 404.
To check this yourself, you can access http://localhost:4502/system/console/servletresolver and add the url to want to check to, the console will tell you which script/servlet will be called to resolve the request in the candidates section
like

We can not get the list of all selectors we want to disallow from servlet but a right approach to handle such cases is to first disallow all selectors from dispatcher filter and then allow only project specific selectors like:
# Deny content grabbing for /content and its subtree
/0031 { /type "deny" /path "/content/*" /selectors '(.*)' /extension '(json|xml|html)' }
# Allow known selectors for /content and its subtree
/0032 { /type "allow" /path "/content/*" /selectors '(nocache|external|internal|footer|media)' /extension '(json|html)' }
Hope it helps!
Thanks!
Nupur