It would be nice if non-existant domains resolved to a CNAME rather than an A record, when forwarding to hit-nxdomain.opendns.com.
Currently, when I PING a non-existant domain, I see the following:
D:>ping non-existant-domain.example.org
Pinging non-existant-domain.example.org [67.215.65.132] with 32 bytes of data:
Reply from 67.215.65.132: bytes=32 time=864ms TTL=54 Reply from 67.215.65.132: bytes=32 time=992ms TTL=54 Reply from 67.215.65.132: bytes=32 time=1329ms TTL=54 Reply from 67.215.65.132: bytes=32 time=1515ms TTL=54
Ping statistics for 67.215.65.132: Packets: Sent = 4, Received = 4, Lost = 0 (0% loss), Approximate round trip times in milli-seconds: Minimum = 864ms, Maximum = 1515ms, Average = 1175ms
Whereas, if it were a CNAME, I'd see:
D:>ping non-existant-domain.example.org
Pinging hit-nxdomain.opendns.com [67.215.65.132] with 32 bytes of data:
Reply from 67.215.65.132: bytes=32 time=864ms TTL=54 Reply from 67.215.65.132: bytes=32 time=992ms TTL=54 Reply from 67.215.65.132: bytes=32 time=1329ms TTL=54 Reply from 67.215.65.132: bytes=32 time=1515ms TTL=54
Ping statistics for 67.215.65.132: Packets: Sent = 4, Received = 4, Lost = 0 (0% loss), Approximate round trip times in milli-seconds: Minimum = 864ms, Maximum = 1515ms, Average = 1175ms
This would make it far more obvious that the address I was pinging did not resolve. Granted this is not as obvious as:
D:>ping example Ping request could not find host example. Please check the name and try again.
but obvious enough, at least.
J.
1 Comment
Currently, when I PING a non-existant domain, I see the following:
D:>ping non-existant-domain.example.org
Pinging non-existant-domain.example.org [67.215.65.132] with 32 bytes of data:
Reply from 67.215.65.132: bytes=32 time=864ms TTL=54 Reply from 67.215.65.132: bytes=32 time=992ms TTL=54 Reply from 67.215.65.132: bytes=32 time=1329ms TTL=54 Reply from 67.215.65.132: bytes=32 time=1515ms TTL=54
Ping statistics for 67.215.65.132: Packets: Sent = 4, Received = 4, Lost = 0 (0% loss), Approximate round trip times in milli-seconds: Minimum = 864ms, Maximum = 1515ms, Average = 1175ms
Whereas, if it were a CNAME, I'd see:
D:>ping non-existant-domain.example.org
Pinging hit-nxdomain.opendns.com [67.215.65.132] with 32 bytes of data:
Reply from 67.215.65.132: bytes=32 time=864ms TTL=54 Reply from 67.215.65.132: bytes=32 time=992ms TTL=54 Reply from 67.215.65.132: bytes=32 time=1329ms TTL=54 Reply from 67.215.65.132: bytes=32 time=1515ms TTL=54
Ping statistics for 67.215.65.132: Packets: Sent = 4, Received = 4, Lost = 0 (0% loss), Approximate round trip times in milli-seconds: Minimum = 864ms, Maximum = 1515ms, Average = 1175ms
This would make it far more obvious that the address I was pinging did not resolve. Granted this is not as obvious as:
D:>ping example Ping request could not find host example. Please check the name and try again.
but obvious enough, at least.
J.
1 Comment
Hmm. I guess the Windows ping utility doesn't attempt a reverse lookup?
Besides, if all you want to know is if it resolves, use nslookup. Then nslookup the resulting IP address to see if it goes back to hit-nxdomain.opendns.com
Using a CNAME can cause other problems, for example if there is no A record for a domain, but other records do exist (like lets say MX) using a CNAME will prevent those records from being seen.
Even if the nameserver could be configured to respond with a CNAME only if an A record was asked for, the risk is still there that the client computer will cache the result ( yes even for longer than the ttl of 0 ) and a subsequent request for the MX record will also come back as a CNAME to hit-nxdomain.opendns.com.
Here is what I got when I tried to ping something obviously non-existant:
joe@epinephrine:~$ ping -c 4 nosuchdomain.blah.invalid.
PING nosuchdomain.blah.invalid (208.69.36.132) 56(84) bytes of data.
64 bytes from hit-nxdomain.opendns.com (208.69.36.132): icmp_seq=1 ttl=57 time=19.5 ms
64 bytes from hit-nxdomain.opendns.com (208.69.36.132): icmp_seq=2 ttl=57 time=19.6 ms
64 bytes from hit-nxdomain.opendns.com (208.69.36.132): icmp_seq=3 ttl=57 time=19.7 ms
64 bytes from hit-nxdomain.opendns.com (208.69.36.132): icmp_seq=4 ttl=57 time=19.7 ms
--- nosuchdomain.blah.invalid ping statistics ---
4 packets transmitted, 4 received, 0% packet loss, time 3001ms
rtt min/avg/max/mdev = 19.529/19.692/19.778/0.101 ms
yeah, there are ping utilities out there that use a reverse lookup. and even if yours doesnt, nslookup is your friend :)