Welcome to PerlMonks!, santoshkumarcp

It will be easier for people to help you if you surround your code (e.g. the part after My code is like this...) with <code>...</code> tags. This will make your code look more like it looks when you type it into the input box. If you can't see the edit box, scroll down a bit in your browser window. If you still can't see it, click on the title of your post.

As for the question itself: you can use the concatenation (dot) operator 'IP_' . $newHosts->{server} to get the sting "IP_10.100.200.10". Further discussion aimed at a beginner can be found at How to concatenate stings with Perl.

Best, beth