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HOST IS DOWN - out of the blue

Posted on 2005-04-07
Medium Priority
Last Modified: 2013-12-23
I was watching TV and my wife was surfing the internet when she said she couldn't get to any more web pages from the internet. I tried connecting to a site on the server and the host name wouldn't resolve. I tried localhost and it won't resolve. The only way I can reach a site on the server is with

I can't access anything on the server from any other computers within our network.

Could this be a DNS/BIND issue. Why would it stop working just like that out of the blue?

Can someone help me trouble shoot???
Question by:HangTenDesign
  • 4
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Author Comment

ID: 13732794
I tried nslookup on the server and it returns the correct information. However, when I try to ping that informaiton I get an "unknown host" return.

Is there some kind of routing problem??? What could this be??? help
LVL 38

Expert Comment

ID: 13732800
>I can't access anything on the server from any other computers within our network.
What kind of machine OS do you have?
Solaris, RedHat Linux or ....
What's the output of
uname -a
ifconfig -a   (as root)
netstat -rn

And also check /var/log/messages (or /var/adm/messages) for error messages.

LVL 38

Accepted Solution

wesly_chen earned 2000 total points
ID: 13732805
> I tried nslookup on the server and it returns the correct information
Check /etc/nsswitch.conf  for
hosts:   files dns     # <== make sure "dns" here
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Author Comment

ID: 13732891


----> OK, so all I did was shut down DNS/BIND and then restart and it did the trick.

Why would a shutdown and restart fix it??? I have found UNIX to be incredibly stable and mostly cause and effect. What could cause it to do such a thing?
LVL 38

Expert Comment

ID: 13732920
> all I did was shut down DNS/BIND and then restart and it did the trick
Well, for MacOS X, you shouldn't need to run BIND (DNS server). I guess some sort of DNS temporary cache
database corrupted cause the problem.

I would recommend that turn off BIND if you don't need it.
Besides, turn off unnecessary services for security.
MacOS X, by default, will start a lot of services (similar to M$ Windows) which you probably won't use them all the time.

Anyway, glad to know your problem resolved so quickly.

Author Comment

ID: 13732949
Yes, thankyou.

BTW, I am running BIND cause I am running my own DNS server, web, mail, database, with over a dozen domains. I couldn't believe how incredibly powerful MacOS X was under the hood. I am not even using their Server software. It's all there!

Thanks again
LVL 38

Expert Comment

ID: 13732967
That's Unix's world. M$ charge every piece they can charge out of users.......

Expert Comment

ID: 13909478
Check if your DNS server is caching negative replies, and whether you have listed the upstream (ISP) DNS server by name or IP address.

If the ISP has a problem for even a brief interval and you specify upstream by name, your DNS server may cache the fact that the ISP's DNS server is unavailable.  Once that happens, until the cache expires, every query for ns.isp.com gets 'not found'.

Restarting bind clears the cache.


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