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AT&T's "dnserrorassist" will not allow local sites to open


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#1 BeckoningChasm

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Posted 20 June 2017 - 01:09 PM

Greetings.  One of our clients has a Lenovo laptop, running Windows 10 latest update (ie, the one where you have to search for Control Panel).

 

At home, his internet service is provided by AT&T. 

 

Just within the last ten days or so, when he brings his laptop to the office, he cannot open any intranet sites in Internet Explorer.  (For a variety of reasons, the developer prefers IE).  Instead, he gets a message page that AT&T can't find this local server.  The web address is dnserrorassist.att.net.

 

I don't understand why AT&T is doing this, or how it is overriding PC settings, or how I can get rid of it.  A Google search seems to say that "opting out" of this service is the only way, but he has tried every username and password he knows and is not getting anywhere.

 

Here's what I've done, not listed in order but as I go back and try to recall what I did--

 

1. Checked DNS.  The only entry (through DHCP) is the local server in the office.  Flushed DNS, it's still the only DNS server.  ATT still comes up.

2. Hardcoded the DNS entries under IP4, using the local server and a Google server.  Flushed DNS and restarted.  ATT still comes up.

3. Edited the HOSTS file so that the server name and IP address are there.  (The only other entry in HOSTS is localhost.)  ATT still comes up.

4. Ran RKILL, ADWCleaner and MalwareBytes.  Very minor stuff found.  Rebooted, ATT still comes up.

5. Checked the registry for any mention of dnserrorassist.  None found.

6. Restored PC to a restore point a few days before all this started happening.  ATT still comes up.

7. Cleared history in IE.  ATT still comes up.

8. Ran IE without any add-ons.  I checked the add-ons that were listed, none of them are AT&T related.  ATT still comes up.

 

Right now, the customer is using Edge, which works (as do other browsers) but is not as functional as IE.  (Yes, I can't believe I typed that either.)

 

What I would like to do is find out where AT&T's stuff is hiding and root it out; barring that, if there's a way to block dnserrorassist.att.net I would do that as well.  As far as I'm concerned, AT&T's behavior fits the definition of "malware" perfectly.

 

Anyone have any ideas? 

 

Please let me know if you need any other details.

 

Thanks in advance for any and all suggestions.

 

PS: Apologies if this is in the wrong forum area.


Edited by BeckoningChasm, 20 June 2017 - 01:10 PM.


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#2 BeckoningChasm

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Posted 20 June 2017 - 01:35 PM

Well, well, well.  Not five minutes after I posted this, the client sent me an email, saying he was no longer being redirected to AT&T's DNS error page.

 

Oops, I guess that one worked out on its own.  Still, I'd be curious to know if anyone could tell me what was going on.

 

Sorry about that, and thanks!



#3 JohnC_21

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Posted 20 June 2017 - 01:37 PM

Take a look here. You are not alone.

 

https://forums.att.com/t5/AT-T-Internet-Features/ATT-DNS-Assist-Page/td-p/5108480



#4 BeckoningChasm

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Posted 20 June 2017 - 02:12 PM

Yes, I saw that discussion.  There are many others like it, on AT&T forums and others.  I've never found anything which explains what AT&T is doing, or how they are hijacking IE.

 

Still, I appreciate the info.

 

Thanks!



#5 JohnC_21

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Posted 20 June 2017 - 02:24 PM

It's really strange. I would have thought adding new DNS addresses and flushing DNS would have solved the problem. 

 

Edit: I have Att UVerse and did not know you could opt out of dnserrorassist. But still, I don't understand how opting out would affect the computer when attached to another network.

 

https://forums.att.com/t5/Internet-and-DSL-Community/How-to-get-rid-of-DNS-Error-Assit/td-p/4879787


Edited by JohnC_21, 20 June 2017 - 02:29 PM.


#6 bahrendt

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Posted 28 August 2017 - 12:46 PM

After many fruitless searches, and countless frustrating calls to AT&T support we think we have found an answer to the dnserrorassist.att.net curse.
 
One of our trips down the rabbit hole led my teammate to this key in the registry: [HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\LowRegistry\DOMStorage\dnserrorassist.att.net]
@=dword:00000047
 
A little digging there pointed to the use of DOM Cookies
 
 
To test this out I used the instructions here to disable DOM Cookies in IE.
 
 
Also, I then cleared the Browsing History
 
IMPORTANT TIP!!!!!!
 
UNCHECK - Preserve Favorites website data
CHECK - Temporary Internet files and website data
CHECK - Cookies and website data
 
We had cleared browsing history so many times in the past, but I had overlooked the "Preserve Favorites website data" option which is checked by default.  Important to note was that the site we continued to have an issue with was indeed saved as a Favorite.
 
In theory, simply clearing the cookie cache might be enough.  We, however, took these steps:
 
1. Disabled DOM Cookies in IE
2. Cleared the Browsing History (including Favorites data)
3. Closed and reopened IE
4. Renabled DOM Cookies
 
All sites worked without the dnserrorassist.att.net redirect.
 
 
THANK GOD!  Time for a drink!
 
 
I hope this information helps someone from wasting time on this useless AT&T "feature".


#7 BeckoningChasm

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Posted 28 August 2017 - 03:23 PM

Outstanding!  Thank you so much for posting the details.  Should this damned thing pop up again (and we've been fortunate lately), I'll know where to look now.

 

Thank you!






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