Server Fault is a question and answer site for system and network administrators. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

I have an ubuntu server ( whose IPv4 address is, with a DNS server for the domain at

When I dig from cygwin on my Windows 7 box, I get the correct answer from the DNS server. When I nslookup, I get "". When I nslookup I get the correct response.

When I ping the server's IP address, I get a response. When I ping just "server01", I get a response.

It's only when I ping the server's fully-qualified domain name "" that I get "unknown host". Does anyone know what the heck could be happening?

P.S. - My real domain name is (obviously) not, but the IP address are real.

Here's the wireshark capture of when I nslookup

53  25.194795        DNS 83  Standard query PTR
54  25.194899    DNS 114 Standard query response PTR
55  25.197525        DNS 92  Standard query A
56  25.197586    DNS 156 Standard query response, No such name
57  25.198567        DNS 92  Standard query AAAA
58  25.198633    DNS 156 Standard query response, No such name
59  25.199559        DNS 79  Standard query A
60  25.199663    DNS 115 Standard query response CNAME A
61  25.200667        DNS 79  Standard query AAAA
62  25.200736    DNS 99  Standard query response CNAME
share|improve this question
Does nslookup return the correct IP address? – Ansgar Wiechers Sep 11 '12 at 1:33
@Ansgar I logged on to get an answer your question and now pinging the FQDN works just fine. I haven't made any changes. I hadn't made any changes when I was first seeing the problem either. It simply went away. – John Ruiz Sep 11 '12 at 19:31

When you do an nslookup [ip address] what you are seeing is the ptr record. But when you do a ping it uses an A record.

You're doing three different tests:

  1. dig is returning the A record (but via cygwin, so it's not a good test of Windows lookup mechanism)
  2. nslookup is returning the PTR record
  3. ping is using Windows name resolution, which is a combination of hosts, netbios, dns and whatever other magical things might be installed.

Try doing an nslookup of nslookup and see what happens then.

share|improve this answer
see my comment above. The problem mysteriously went away without me doing anything. So. Strange. – John Ruiz Sep 11 '12 at 19:32
Okay, the behavior is back! When I nslookup, I get this: Server: Address: Name: Address: Aliases: – John Ruiz Oct 19 '12 at 21:49
up vote 1 down vote accepted

This behavior is still happening to me off and on. This latest time, I found this technet thread and tried turning off the dnscache service, which fixed the issue.

This seems like a bug in the Windows DNS client/cache.

net stop dnscache
net start dnscache
share|improve this answer

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.