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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 ?

Michal S.
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  • Maybe they both use the same server? – Charlotte Dunois Nov 27 '16 at 17:46
  • what's wrong with ip ? ... it just both of them points to the same server.. any web-server allowing this... anyway pingdom.com hosted via 104.20.61.84 – Wizard Nov 27 '16 at 17:46
  • @Wizard Yes, pingdom.com points to this ip, but in my test i'm checking what is the domain of `69.64.56.153` ip address (basing on https://my.pingdom.com/probes/ipv4 I expect that it belongs to *.pingdom.com domain), but `gethostbyaddr('69.64.56.153');` returns not trusted domain as I wrote in my question so test failed. At the moment i cannot ensure that this IP belongs to pingdom. – Michal S. Nov 27 '16 at 17:58
  • @Cone, looking up hostnames by IP address is not always reliable. What are you trying to accomplish by doing this? – ChrisGPT was on strike Nov 27 '16 at 18:15
  • @Chris It is something like firewall in the application side. I allow some actions for this IP and domain ensures me that request comes from Pingdom. How can I do this on the other way ? – Michal S. Nov 27 '16 at 18:38

1 Answers1

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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).

Dusan Bajic
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