I noticed I was getting udp traffic on random ports from an unknown ip address that was definitely not on my domain today. When I looked up the ip using nslookup, it returned a name. But when I did a whois on both name whois complained that the name had expired and didn't give me back any information. So I tried the ip on whois, and whois couldn't find it at all.
How is this possible?
I want to see what nodes exist under a certain domain from within the domain. Short of querying every valid IP address within that domain, is there a way to get all records/map the network?
I'm writing a simple client to ping a server with a packet on port 7 (echo) and then waiting for a reply. Is there a server that I can use to test this?