Hunting Down a Bogus IP

Filed under Networking, Troubleshooting

I was working on a server issue this morning when I ran into something strange. I could no longer access a server that had been running for quite some time without any problems.

I tried a PING and got back an IP address for the server that made no sense at all. It wasn’t even part of my local IP range!

So I did all the normal stuff:

  1. Checked my HOSTS file
  2. ran IPCONFIG /FLUSHDNS
  3. ran IPCONFIG /REGISTERDNS
  4. ran IPCONFIG /RELEASE
  5. then IPCONFIG /RENEW

No joy. A ping was still returning the same bogus address.

So I checked my server’s DNS service. Not even an hit of that address.

Hmmm. So, where the heck was it coming from? A little googling didn’t turn up much, but eventually, I read a blog post that made an offhand mention of WINS.

Now, I don’t really know all that much about WINS. Just never had a reason to, I suppose. Mostly, I’ve always relied on and stuck with plain DNS. But, Ok, I’ll check it.

Go over to my server, and load up the WINS app (it’s under Admin tools)

image

The left hand window was completely blank. It took a second to realize I had to “query” to retrieve the WINS records, they aren’t automatically just shown.

image

And AHA! There, in the result list of “Active Registrations” was the bogus address for my server. (I’ve already removed it in the image below, but it was in the highlighted column).

image

Case closed. I’m still wondering what changed that suddenly, WINS was being used to resolve the server name when it must have not been before. The only thing I can think of is changing internet providers to Verizon FIOS from Time Warner Cable, and the resulting swap out of the main incoming router.

Granted, for a seasoned network guy, this is likely old hat. But for a software dev who only moonlights as a network guy, it might be some useful information!

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