Proxy autodiscovery via dns not working for XP

[David Beaven]

What is the best way to troubleshoot IE6 not obtaining proxy autodiscovery
from a W2K dhcp server? We have about ten XP (no W2k) machines that all
simultaneously stopped working but it still works for most XP & W2K clients
(150 plus). We have two dns servers both set up as per Q252898. All users
are power users on the pcs so XP machines should be ?ok as per Q312864. If
we set the automatic configuration script manually these clients start
working.

Is this a permissions issue?
Thanks
David

 

[Bob Qin [MSFT]]

Hi David,

Thanks for posting here!

I recommend that you search the wpad.dat file on the Windows XP computer
and check if the configuration file has been download to client. You can
also clear the Temporary Internet files and try again.

In addition, please add the current user to Administrators group or Network
Configuration Operators group. What is the result?

If problem still occur in Administrators group, maybe we need to use
Network Monitor to trace the whole process and check if we can find any
clue in.

Thank you for using our newsgroup.

Regards,
Bob Qin
Product Support Services
Microsoft Corporation

Get Secure! - www.microsoft.com/security

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[David Beaven]

We don't have a wpad.dat file on the machine.
Making the user an admin doesn't work either.
Looking at a netmon trace on a machine that works I can't see where the
request is made to the dhcp server. The proxy entry doesn't appear to be in
the the initial dhcp discover traffic whereas when IE starts it sometimes
says it is detecting proxy settings (in which case there should be traffic
to the dhcp server but i don't see it!).
Do you know where the location of the pac file is stored on the machine
(registry, dat file) and how do you force IE to rediscover the proxy.
Any other ideas?

Thanks
David

 

[Bob Qin [MSFT]]

Hi David,

Thanks for your reply.

Since the problem still occurs after adding the user to Administrators
group, the problem should be related to the local computer network settings.

Is there any difference in Software Configuration between the Windows XP
computer with problem and the other Windows XP computer without problem?
Any difference in the TCP/IP settings (DNS, WINS, Firewall Client
configuration)?

Do you set the proper domain suffix configured in the Internet Protocol
(IP) properties of these computers?

More information:
The PAC file is used in the autoproxy feature. In this configuration,
Internet Explorer caches the .pac file from the server. If you restart
Internet Explorer, the cache is flushed

If "Automatically Detect Settings" is turned on in Internet Explorer, an
attempt is made to download the Wpad.dat file from the local area network
(LAN) and process it as an automatic proxy configuration script. If a
proxy is returned from the script and Internet Explorer has established a
connection through the proxy, the Automatic Proxy Result Cache is updated
with the host and the proxy server name that was returned.

I have included the following articles for your reference:

Description of WinSock Proxy Auto Detect Support
http://support.microsoft.com/?id=260210

A Description of the Automatic Discovery Feature
http://support.microsoft.com/default.aspx?scid=kb;EN-US;296591

Wish it helpful!

Regards,
Bob Qin
Product Support Services
Microsoft Corporation

Get Secure! - www.microsoft.com/security

====================================================
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that others may learn and benefit from your issue.
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[Alan Wood [MSFT]]

Hi All,
Can you verify that from one of the Non Working clients can put path
statement from DHCP in the run line and is able to dowload the wpad.dat?
Does it work with DNS Setting for WPAD.DAT?

Depending on were is kept it has to download.

Example:
DNS
HTTP://wpad/wpad.dat

If you can't download from that then or the path specified it isn't going
to work.

The DHCPinform packet should come from the system "only after" all
instances of IE have been closed.
The best test I could find for that is if taking a network trace, make sure
just to log off then log on the client, then take the trace.

I may have missed it in the thread but in the OS there permissions issue
with using the DHCP method..


Hope this Helps!

Alan Wood[MSFT]

This posting is provided "AS IS" with no warranties, and confers no rights.