In batch, How can i create an IF statement that checks if a variable includes a specific string or data? -

i want make basic pinger in batch learning project , came problem.here code:

@echo off color b title pinger v1.0  :ok echo. echo. set /p t=target i.p.: echo. echo. echo not ip address! echo. goto ok set /p a=packet size: echo. :start set ifer= set /p ifer=start ping (y/n): if %ifer%==y goto 8 if %ifer%==y goto 8 if %ifer%==n goto ok if %ifer%==n goto ok :8 echo. echo. echo. echo. ping %t% -t -l %a% 

my question is, how can check if t contains valid ip address not random data? , also, how can make code translates web address ip address(don't have answer though)