How to troubleshoot a WPAD failure caused by a DHCP server disabling NetBIOS functionality

Today's blog post is just a matter of trying to put the WPAD value out of the way that the Windows XP SP3 version that caused by disabling the NetBIOS option on the DHCP server has been recently encountered.

About disabling the client's NetBIOS option feature, Microsoft Official also has a corresponding solution, here simply mention, the configuration method is as follows, also can refer to Microsoft KB313314 in the explanation to configure, address for http://support.microsoft.com/kb/313314.

Click Start/Administrative Tools, and then click DHCP.

In the DHCP console, expand Scope, right-click Scope Options, and then click Configure Options.

Click the Advanced tab, and then click Microsoft Windows 2000 options in the Vendor Categories list.

Ensure that the default user class is selected in the User categories list.

Then select the 001 Microsoft disable Netbios options check box under the Available Options column.

In the data entry area, type 0x2, and then click OK.

But when we disable the client's NetBIOS functionality through a DHCP server, we find a very interesting problem, that is, if your client has a FWC client installed to discover the TMG server, then Windows 7 and Windows XP SP2 versions are unaffected. But if the enterprise has installed the latest SP3 patch pack for Windows XP clients, then it's time to notice that the NetBIOS feature on the Windows XP SP3 client is disabled, but FWC can't find TMG. If the option to disable NetBIOS functionality on the DHCP server is canceled, Windows XP SP3 immediately discovers the TMG server and is surfing the web, which is interesting, when the problem was discussed with Microsoft engineers, and Microsoft engineers also helped with the query, The result of the feedback is that the Microsoft Windows XP SP3 related document does not mention this problem, that is the wood has the way, can not not install SP3 bar, so we still need to see the relevant solution?

In fact, you can use the following methods to do some basic checks

1, the use of fwctools for inspection, found that the client returned the following content, it is obvious that the client did not download the normal application to the WPAD value OH:

2, the client manually point to the TMG server found that the normal TMG server can be found and online, the initial determination is not caused by TMG.

3. The value set when the NetBIOS option is disabled on DHCP, and the Windows XP SP3 client automatically discovers TMG by DHCP, then it is certain that it is not caused by TMG.

4, on the client installation grab software, at that time I used the Wireshark to carry out the bag, the analysis results are as follows:

5, retrieve the IP address for grasping the package, the Windows XP client has the following prompts: