Government websites

How do u discover the IPs of government websites? You cant ping them they r not publicly available is there another way?

You can use other tools to find the IP of any website. Try checking the reverse domain lookup - it will tell you the IP address block used by the website. You can also use traceroute to see which route traffic takes to reach the destination. It will give you all the IP addresses it goes through.

What if u dont know the domain name or ip address? U know the name and physical location of the office that uses that domain

You can try doing physical pentesting (with their permissIon obviously). Google what physical pentesting is.