Windows 7 Network Resources Disappearing

[larryluckham]

We are having a problem with network resources randomly disappearing and reappearing on several Windows 7 computers on our LAN. Let me define the environment.

Domain LAN with 7 Windows 2003 32 bit servers, including a DC, DHCP, etc.
Desktop computers including 4 Windows 7 Ultimate 64 bit plus a half dozen XP
We run an SUS and all machines are up to date on patches, etc.

The problem is that the Win 7 machines will lose track of network resources from time to time, only to have them reappear for no apparent reason later. In one minute expanding "Network" shows all the appropriate resources, i.e. other machines, etc. and 10 minutes later doing the same expand shows only the local machine and one of the other Win 7 machines. Another 10 minutes and they are all back. This does not affect mapped network drives, and using the Link Removed will find the appropriate resource. But, mapping a new network share from windows explorer isn't possible because the resources fail to appear in the browse window. Command line still works, but this isn't the way it's supposed to work.

Elsewhere I found a suggeation the changing the registry parameter HKEY_LOCAL_MACHINE-> SYSTEM -> CurrentControlSet -> Services ->LanmanServer -> Parameters ->Size from 1 to 3 (1 = use minimum memory, 3 = use maximum) would help. I did make that change and thought it worked, but apparently not. (The machine on which I tried this has 12GB of memory)

I also found a suggestion that disabling the Windows Live Sign In Assistant would help. Just did that. Network is expanded now, but not sure if it's the result of this change, or if it will stay expanded.

So, what gives, and what's needed to correct this mystery coming and going?

 

[Trouble]

The only thing I can think of is that the issue on the Windows 7 machines has to do with name resolution. So;
make sure that all the Win7 machines on point at and only at the server responsible for resolving DNS names for your domain, presumably your DC or another server hosting DNS, and enable NetBIOS over TCP/IP in the properties of IPv4 under the WINS tab. Other than that, if you have a WINS server running, make sure that the machines have that information in the WINS tab.
Are the "resources" that go missing all server based resources (server names) or are they scatter throughout the network and hosted on other non-server machines, if so make sure that the machines pretending to be servers have static IP addresses so as not to contaminate the local DNS cache or NetBIOS cache with erroneous FQDNs to IP addresses or NetBIOS names to IP addresses. Seems simple and straight forward and you've probably already done this, but I thought I would mention it anyway just in case. Because I've seen more than one network setup with DHCP address on DCs and even on DNS servers, despite the warnings during the setup process.

 

[CommonTater]

Make sure network discovery is enabled in your File and Sharing -> advanced section. Also if you're using mixed OSs (as you are) you should be sure that username/password sharing is enabled. I'm guessing you've already figured out you can't use Home networking with mixed OSs.

Also be sure the Computer Browser service is on automatic and running.

 

[larryluckham]

Thanks for the suggestions and I appreciate the quick response. Most of what you suggested has been checked. We don't have any legacy names so no WINS, NetBIOS is enabled, the DNS server seems to be registering names correctly, and network discovery is enabled. The servers all have a static IP, but most also have a second network connection that is DHCP assigned as well. So, from each server's dual port NIC one port is static and the other is DHCP assigned. That is true of both the DC and BDC which are responsible for DNS service as well. DNS is set to listen on both ports, but I'm wondering if there could be a problem with that which would lead to differnt results depending on which port handled a particular request. I'll try resetting the second (DHCP) port to a static address on the DC and see if that helps.

 

[CommonTater]

It seems likely the net enumerator (Computer Browser, SSDP, Network Location Awareness) would be confused by a different port handling the same request... I'm not exactly sure how smart the Browser service is about that.

I usually run any server machines on static IP... It's just a whole lot simpler to debug.

Any hard wired machines can be static or DHCP reservation so they always have the same IPs.

On a LAN you really only need DHCP for people "guesting in" on wireless.

 

[larryluckham]

We always run servers with static IP's. While it's true that on a small LAN, and this is one, setting everything to static is clearly an option. With larger networks managing the IP's becomes a problem and since you almost always have to have the DHCP service running somewhere on the LAN it just becomes easier to let it do the assigning.

So, as to the current issue, I disabled the secondary (DHCP assigned) IP's on the second NIC for both the DC & BDC. Let's see if that makes a difference.

 

[Trouble]

When the Configure Your Server Wizard installs the DNS service, it first determines whether the IP address for this server is static or is configured automatically. If your server is currently configured to obtain its IP address automatically, the Configuring Components page of the Windows Components Wizard prompts you to configure this server with a static IP address.

SOURCE: How To Install and Configure DNS Server in Windows Server 2003
I haven't ever attempted to use a DHCP configured NIC to bind DNS to, it just seems that since it's subject to change that it would only complicate and confuse clients and potentially the server itself as to where to look for name resolution.

 

[CommonTater]

The DNS would likely be handled by a switch or router, Trouble. Setting up a DNS server on the server machine absolutely needs a fixed IP if the clients are to find it.

For Larry... I've run fixed IPs on networks as large as 80 and 90 machines... As long as nobody messes with settings is works perfectly.

 

[larryluckham]

I've never really liked having a router handle DHCP. Likewise, my preference has been static IP's on servers, or specialied connected devices, and DHCP for the rest. Not arguing better or worse, just personal preference.

As to the second NIC having a DHCP assigned address, this should not have happened. We intended to provide those for file and media servers to provide a degree of redundancy and to double the pathway, but the same got applied to the DC and BDC inerror. Let's see if clipping this solves the problem.

 

[CommonTater]

Once an IP is assigned, DHCP or not, is no issue at all. My preference has been to use static IPs because you can tell at a glance which machine is causing problems... "Oh it's #34 over in the coffee shop..." etc.

Let me know how you make out... clearly there's some strangeness going on...

 

[larryluckham]

I definitely understand your point Tater. As long as you have good administrative control of the network and are willing to maintain control of the address assignments so that you don't accidentally end up with duplicates, or other problems, I can see that it could work quite well. I many environments there can be several people involved in network maintenance issues and the element of administrative control is lost.

As to the problem of this thread, so far, knock on wood, the resources seem to be staying visible, but I'll give it a few days before declaring the problem resolved.

 

[CommonTater]

I definitely understand your point Tater. As long as you have good administrative control of the network and are willing to maintain control of the address assignments so that you don't accidentally end up with duplicates, or other problems, I can see that it could work quite well. I many environments there can be several people involved in network maintenance issues and the element of administrative control is lost.

That is a matter of setting policy... and getting really angry at people who ignore it ^^

As to the problem of this thread, so far, knock on wood, the resources seem to be staying visible, but I'll give it a few days before declaring the problem resolved.

Smart move. Glad it's going...

 

[CommonTater]

I haven't ever attempted to use a DHCP configured NIC to bind DNS to, it just seems that since it's subject to change that it would only complicate and confuse clients and potentially the server itself as to where to look for name resolution.

Exactly ... if they can't find the name server...

 

[larryluckham]

Thought I'd post a follow up to close this out. Not sure exactly what solved the problem, or if it was the combination of small adjustments, but network resources haven't disappeared for a number of days now and that was not the history prior to troubleshooting.

 

[CommonTater]

Thought I'd post a follow up to close this out. Not sure exactly what solved the problem, or if it was the combination of small adjustments, but network resources haven't disappeared for a number of days now and that was not the history prior to troubleshooting.

Excellent...