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Suppose I own the domain example.com and control its DNS server. (To be clear, I do not own example.com.)

I just recently (about an hour ago) updated the dns for a.example.com to point at the IP address of a Linode that I am renting. Note that a.example.com previously did not point at anything.

Now, on localhost, I try the command ping a.example.com and get the error unknown host a.example.com. This is suprising to me, because I had just pointed the subdomain and I do not expect there to be cache of the domain already in the recursive resolver at any level. More specifically, I would expect one of the recursive resolvers upstream of me to query the authoritative nameserver (which I just configured), and discover the correct IP Address.

As an additional experiment, I tried the same command ping a.example.com from a different virtual server in Digital Ocean's cloud, and it resolved to the correct IP address.

Why are some reasons that localhost might fail to see the new DNS entry?

How might I force localhost to see the DNS entry for the subdomain?

Note that I am using Google DNS and running Ubuntu 14.04 on localhost.

  • Since foo.com is a real domain owned by a real organisation you might want to choose a different one. example.com perhaps? – roaima Apr 10 '15 at 0:14
  • @roaima, Given that I've already indicated that I do not own the domain, is this relevant to the question? – merlin2011 Apr 10 '15 at 0:15
  • It's not relevant to the question but it might be relelvant to the domain owner, which is why I raised it. Either way, I'm still pondering your underlying issue. Can you offer your real domain record, please? So's I can review the DNS records, glue, etc. – roaima Apr 10 '15 at 0:23
  • posting the output of dig a.foo.com from localhost might help; about your second question, edit /etc/hosts while you don't get the hostname resolved correctly. – guido Apr 10 '15 at 0:24
  • @guido, I just looked at the dig entry and it is pointing at something completely random. There's something strange happening upstream. – merlin2011 Apr 10 '15 at 0:27
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If you updated one hour ago maybe the propagation isn't finished yet?

You might want to check what's my dns to be sure that your new dns resolution has spread everywhere.

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