How is it possible that two hosts indicates the same ip address? When I'm trying to ping the s482.pingdom.com it returns the IP as below
ping s482.pingdom.com
PING s482.pingdom.com (69.64.56.153): 56 data bytes
64 bytes from 69.64.56.153: icmp_seq=0 ttl=46 time=146.010 ms
But when i'm trying ping the usloft1473.serverprofi24.eu it returns the same IP
ping usloft1473.serverprofi24.eu
PING usloft1473.serverprofi24.eu (69.64.56.153): 56 data bytes
64 bytes from 69.64.56.153: icmp_seq=0 ttl=46 time=148.226 ms
I've noticed the problem because tests in my application have been failing since yesterday due to PHP function gethostbyaddr($ip); where test assumes that this IP is connected with pingdom domain.
In addition, what is interesting that traceroute s482.pingdom.com stops on usloft1473.serverprofi24.eu node.
What's happened ?
It is very common that several host names point to same IP address.
Also, as @Chris said, using reverse DNS lookup to determine the owner of an IP address is more then unreliable. One possible way to go would be to check (perhaps with their support) if Pingdom publishes the list of IP ranges they use (even that might be difficult since those ranges could change frequently).