Connect via IP, but not NetBIOS?

March 18, 2008 12:41 PM

Why would I be able to connect to other Windows computers in a workgroup via IP, but not by NetBIOS name?

I have a pool of about 25 laptops that I use at various events around the country. Some of them have randomly been having an issue accessing any other XP machine on a workgroup (non-domain environment) by NetBIOS name.

For example, if in Windows Explorer I browse to "\\ComputerName\" in the address bar, I get an error. Yet if I put in "\\192.168.50.x" (x being that same machine's IP), it works fine.

File and Printer Sharing for MS Networks is installed for the network device. I've read something about needing a "master browser" but all the other machines in our office network are working fine. I've blown out and reinstalled the PCs that this has happened to and it has solved the issue, but I'd like to avoid having to do this every so often for no apparent reason.

What would cause this and how can I fix it? Thanks!!

posted by Ekim Neems to computers & internet (9 comments total)

Are these laptops connected to your office network when not on the road with you? If so, does your office use a workgroup or a domain, and do you use static or dynamic IPs? It's possible that it's just outdated entries in the NetBIOS cache if a machine's IP address changes. You can reset a particular machine's cache with "NBTSTAT -r" from the command prompt.

What error do you get when you try to connect by NetBIOS name?
posted by XcentricOrbit at 1:12 PM on March 18

They are connected to the network when not in the road, but they all have the same workgroup name - the only difference being physical location and the actual switch (onsite, I use a simple switch with manual IPs - in the office, I have a router with DHCP but the laptops often stay manual IP).

The error I get is "Windows cannot find \\computer\ - check the spelling or try again" - When I try to view workgroup computers, I get a permissions error.

It's worthy to note that when I connect via the wireless card, it doesn't work. I've also taken one that does still work and compared all the advanced TCP/IP settings side by side and everything seems to be the same. My guess is that it's not a connection/adapter specific issue, but something with Windows as it doesn't work across multiple adapters.

I did check to see that the Computer Browser service is started, and it indeed is. And lastly, even though Windows Firewall is disabled I checked to make sure it wasn't blocked in those settings either.
posted by Ekim Neems at 1:17 PM on March 18

Is your firewall (lan, not Windows Firewall) blocking it? I've had that happen to me. I think they are ports 138 & 139.
posted by cdmwebs at 1:22 PM on March 18

Can't be the router, because when used at the events, it's only a simple switch connection the machines and the others will work fine (and I can still access directly via IP address).
posted by Ekim Neems at 1:30 PM on March 18

Hmmm. And you've enabled "Enable NetBIOS over TCP/IP" on that second or third tab of Advanced settings?
posted by cdmwebs at 1:46 PM on March 18

Go to C:\WINDOWS\system32\drivers\etc and check for an lmhosts file. Unless you manually set up a configuration, all the lines should be commented out (preceded by #).
Alternatively, if you do use static IPs, you could map the netbios names to their IP using lmhosts...

There's some stuff with NSLOOKUP that could help, but I'm out of time and don't have a workgroup computer up and running to test my theory on.
posted by jmd82 at 1:51 PM on March 18

Yeah, it is enabled. The strange thing is that this has randomly happened on a few of our laptops - they're all Dell Inspiron 6000s, 1501s, or 1300s. They all use the same software... pretty basic. Norton Antivirus 10 corporate (no firewall built in), Microsoft Office, Microsoft SQL Server 2000 Personal, and that's about it.

If it only happened once, I would've blown it out and have been done with it (which I did the first time), but we're on our 4th one that's done this so I'm starting to worry.
posted by Ekim Neems at 1:52 PM on March 18

The problem is that you are not on a domain, thus you dont have a WINS server. What windows does in a workgroup is elect a computer to to be a 'master browser' to resolve these names. This works in theory, in practice it works pretty crappily. I'm not sure how discovery works with this setup, but imagine the stock windows firewall settings would block it. I'd unlock file and print sharing and try it again, but if the master browser is being shut off at random times or is having firewall/network issues or whatever then the rest suffer. I'm also not sure how often discovery happens, so it may be that your laptop might need to be on the network for an hour or so before the master browser can detect and update itself.

>My guess is that it's not a connection/adapter specific issue, but something with Windows as it doesn't work across multiple adapters.

I'd also be worried that if you first get on the network with the wireless card and broadcast mac, computer name, etc and that fails then plug into the network the browser service/master browser may not get updated because you already said "hey im here" over the wireless, which failed.
posted by damn dirty ape at 2:34 PM on March 18

You can troubleshoot this with browstat. More info here:

http://support.microsoft.com/kb/188305
posted by damn dirty ape at 2:36 PM on March 18