[isalist] Re: Strange Behaviour in ISA2006

From: Amy Babinchak <amy@xxxxxxxxxxxxxxxxxxxxxxxxxx>
To: "isalist@xxxxxxxxxxxxx" <isalist@xxxxxxxxxxxxx>
Date: Thu, 5 Mar 2009 19:44:11 -0500
Isn't there a current known issue about not being able to resolve top level 
domain names? I'm pretty sure that there's a kb out there on it already.

thanks,

Amy Babinchak

Harbor Computer Services | 248-850-8616

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From: isalist-bounce@xxxxxxxxxxxxx [mailto:isalist-bounce@xxxxxxxxxxxxx] On 
Behalf Of Steve Moffat
Sent: Thursday, March 05, 2009 7:40 PM
To: ISA Mailing List
Subject: [isalist] Re: Strange Behaviour in ISA2006

I have never ever used forwarders and never had 1 dns issue at all ever...

From: isalist-bounce@xxxxxxxxxxxxx [mailto:isalist-bounce@xxxxxxxxxxxxx] On 
Behalf Of Ball, Dan
Sent: Thursday, March 05, 2009 4:14 PM
To: ISA Mailing List
Subject: [isalist] Re: Strange Behaviour in ISA2006

No, I have not tried it yet... I remember there was a serious debate on this 
list a few years ago whether using only root servers was beneficial or not, and 
I believe it ended in a stalemate.  Since then, I have not revisited that 
issue.  Besides, if I have four forwarders and all of them lock out my ISA 
server, what benefit would I get from having every root server on the Internet 
block me other than global recognition?   I believe I have a problem with 
something on my network that is flooding the forwarders and causing them to 
lock me out, so by changing to the root servers I'm only reducing the effect, 
not fixing the problem.

In any case, I've been spending my time lately partitioning out my internal 
network so I can try to isolate the issue some more.   The sheer volume of 
traffic here makes it difficult to find the culprit(s) with the little time I 
have to spend on it.


From: isalist-bounce@xxxxxxxxxxxxx [mailto:isalist-bounce@xxxxxxxxxxxxx] On 
Behalf Of Steve Moffat
Sent: Thursday, February 26, 2009 4:29 PM
To: ISA Mailing List
Subject: [isalist] Re: Strange Behaviour in ISA2006

Too easy....

From: isalist-bounce@xxxxxxxxxxxxx [mailto:isalist-bounce@xxxxxxxxxxxxx] On 
Behalf Of Crockett, Gregory
Sent: Thursday, February 26, 2009 4:25 PM
To: ISA Mailing List
Subject: [isalist] Re: Strange Behaviour in ISA2006

Have you tried deleting your forwarders and use just the DNS root servers?

From: isalist-bounce@xxxxxxxxxxxxx [mailto:isalist-bounce@xxxxxxxxxxxxx] On 
Behalf Of Ball, Dan
Sent: Thursday, February 26, 2009 1:26 PM
To: 'isalist@xxxxxxxxxxxxx'
Subject: [isalist] Re: Strange Behaviour in ISA2006

Yep, when contacting all of our normal forwarders, I get query refused.  When I 
changed to the Verizon DNS server, the query went through.   Something is 
definitely causing our DNS forwarding servers to start blocking us for a period 
of time.


From: isalist-bounce@xxxxxxxxxxxxx [mailto:isalist-bounce@xxxxxxxxxxxxx] On 
Behalf Of Ball, Dan
Sent: Friday, February 13, 2009 6:40 PM
To: 'isalist@xxxxxxxxxxxxx'
Subject: [isalist] Re: Strange Behaviour in ISA2006

That was from behind the ISA server, from in front of it the same DNS responds 
fine.  Trying to figure out why the DNS servers stop responding to requests 
coming from the ISA server.   I'll try the Verizon server next time to see if 
that will pass through.



From: isalist-bounce@xxxxxxxxxxxxx [mailto:isalist-bounce@xxxxxxxxxxxxx] On 
Behalf Of Jerry Young
Sent: Wednesday, February 11, 2009 10:40 AM
To: isalist@xxxxxxxxxxxxx
Subject: [isalist] Re: Strange Behaviour in ISA2006

Did you do this from in front or behind the ISA Server?

The query refused response indicates the DNS server chose not to respond to 
your query; that's got nothing to do with ISA, I don't think.

The most common cause of a query refusal that I've run across is when a 
secondary DNS server can't pull updates from the primary DNS server (for some 
reason the zone transfer failed) and so shuts down the zone.

Try using the DNS server 4.2.2.2 (Verizon) the next time to see if that box 
also exhibits the same query refused response.
On Tue, Feb 10, 2009 at 9:17 AM, Ball, Dan 
<DBall@xxxxxxxxxxx<mailto:DBall@xxxxxxxxxxx>> wrote:

Okay, was able to run some tests today during a DNS outage.



Telnet to DNS server, connected okay.



Using NSLOOKUP interactively gave the response of "Query refused" on each of 
the forwarders.



Any further testing was cut short because I logged into the ISA server via RDP 
and, like usual, the situation cleared immediately.





From: isalist-bounce@xxxxxxxxxxxxx<mailto:isalist-bounce@xxxxxxxxxxxxx> 
[mailto:isalist-bounce@xxxxxxxxxxxxx<mailto:isalist-bounce@xxxxxxxxxxxxx>] On 
Behalf Of Ball, Dan
Sent: Friday, January 30, 2009 2:01 PM
To: 'isalist@xxxxxxxxxxxxx<mailto:isalist@xxxxxxxxxxxxx>'
Subject: [isalist] Re: Strange Behaviour in ISA2006



Yes, the computer I put on the "outside" is on the same sub-net as the ISA 
server is.



Thanks, your input has given me a much shorter list of things to test the next 
time this occurs.





From: isalist-bounce@xxxxxxxxxxxxx<mailto:isalist-bounce@xxxxxxxxxxxxx> 
[mailto:isalist-bounce@xxxxxxxxxxxxx<mailto:isalist-bounce@xxxxxxxxxxxxx>] On 
Behalf Of Jerry Young
Sent: Thursday, January 29, 2009 3:19 PM
To: isalist@xxxxxxxxxxxxx<mailto:isalist@xxxxxxxxxxxxx>
Subject: [isalist] Re: Strange Behaviour in ISA2006



If telnet isn't working but yet you're seeing it pass through the ISA server, 
it seems more likely that some kind of assymetric route is in play - this can 
occassionally occur with bad BGP routes between peers.



When you put a client on the outside of the ISA server, is it in the same 
external network that the ISA server is?

On Thu, Jan 29, 2009 at 3:05 PM, Ball, Dan 
<DBall@xxxxxxxxxxx<mailto:DBall@xxxxxxxxxxx>> wrote:

I did try to telnet, and that didn't work, and I did try nslookup with manually 
configuring multiple servers, they all timed out.  I don't think I tried 
manually setting a DNS server that wasn't one of our normal ones though,  so 
I'll have to try that next time.



As for routing, the DNS traffic makes it to the ISA server and goes out to the 
Internet, I can see it in the logs, it just doesn't seem to come back.





From: isalist-bounce@xxxxxxxxxxxxx<mailto:isalist-bounce@xxxxxxxxxxxxx> 
[mailto:isalist-bounce@xxxxxxxxxxxxx<mailto:isalist-bounce@xxxxxxxxxxxxx>] On 
Behalf Of Jerry Young
Sent: Thursday, January 29, 2009 2:02 PM
To: isalist@xxxxxxxxxxxxx<mailto:isalist@xxxxxxxxxxxxx>
Subject: [isalist] Re: Strange Behaviour in ISA2006



Dan,



From the clients on the inside of the ISA Server try the following command.



telnet <dns server ip address> 53



Does that work?



If it does, try the following:



nslookup www.yahoo.com<http://www.yahoo.com/> <dns server ip address>



Does that work?



If not, try using nslookup interactively and see what kind of error message you 
get when you attempt to set the server to the DNS server IP address.



Since this is happening intermittently, it may actually be a network routing 
issue as opposed to an ISA server issue.  I don't know what kind of topology 
you have in place on the inside of your ISA server but do take a look at that.

On Thu, Jan 29, 2009 at 1:53 PM, Ball, Dan 
<DBall@xxxxxxxxxxx<mailto:DBall@xxxxxxxxxxx>> wrote:

http://www.ISAserver.org<http://www.isaserver.org/>
-------------------------------------------------------

It seems to happen no matter what DNS servers I put in as forwarders, and we 
cannot function without them (need to get DNS resolution somehow!).


-----Original Message-----
From: isalist-bounce@xxxxxxxxxxxxx<mailto:isalist-bounce@xxxxxxxxxxxxx> 
[mailto:isalist-bounce@xxxxxxxxxxxxx<mailto:isalist-bounce@xxxxxxxxxxxxx>] On 
Behalf Of Crockett, Gregory
Sent: Tuesday, January 27, 2009 2:30 PM
To: isalist@xxxxxxxxxxxxx<mailto:isalist@xxxxxxxxxxxxx>
Subject: [isalist] Re: Strange Behaviour in ISA2006

http://www.ISAserver.org<http://www.isaserver.org/>
-------------------------------------------------------

What happens should you kill your isp dns servers as forwarders?  I have never 
used our isps dns servers as forwarders.

Sent from mobile outlook.

-----Original Message-----
From: Ball, Dan <DBall@xxxxxxxxxxx<mailto:DBall@xxxxxxxxxxx>>
Sent: Tuesday, January 27, 2009 1:12 PM
To: 'isalist@xxxxxxxxxxxxx<mailto:isalist@xxxxxxxxxxxxx>' 
<isalist@xxxxxxxxxxxxx<mailto:isalist@xxxxxxxxxxxxx>>
Subject: [isalist] Re: Strange Behaviour in ISA2006

Been too busy to play with this much lately, basically I've been just waiting 
it out whenever it has happened, it eventually clears itself.  Just now it 
happened again though, and I happened to be logged into the ISA server at the 
time, so I did some packet captures in case someone asked for them.

Otherwise, I have tested the DNS servers out pretty good, and the problem 
appears to be in the ISA server.  The internal servers cannot contact the 
forwarders, so they dish out responses until the cache times out and then start 
sending out host-not-found messages instead.  While this is going on, I can 
take a computer on the other side of our ISA server and connect to the DNS 
servers on the forwarders list, so I know they are alive and kicking, the DNS 
queries just are not passing through the ISA server.  As long as the computers 
know the IP address, they can continue to communicate through the ISA server, 
they just cannot look up any new addresses.

I see a bunch of alerts saying "ISA Server detected an all port scan attack..." 
from the forwarders IPs addresses immediately prior to and during the problem.  
I remember from awhile back that this was a common message from DNS server, 
would the ISA server block those IPs for a time in response to those scan 
attacks?


From: Ball, Dan
Sent: Thursday, November 06, 2008 12:52 PM
To: 'isalist@xxxxxxxxxxxxx<mailto:isalist@xxxxxxxxxxxxx>'
Subject: RE: [isalist] Re: Strange Behaviour in ISA2006

Yes, there are two DNS servers on the internal network that the ISA server is a 
part of.  All workstations (including the ISA server)  are pointing to these 
two DNS servers, no external DNS serves are configured except as forwarders on 
those two DNS servers.  If any DNS request is made that is not part of the 
local network, they use forwarders to resolve the address from our ISPs DNS 
servers.


From: isalist-bounce@xxxxxxxxxxxxx<mailto:isalist-bounce@xxxxxxxxxxxxx> 
[mailto:isalist-bounce@xxxxxxxxxxxxx<mailto:isalist-bounce@xxxxxxxxxxxxx>] On 
Behalf Of Jerry Young
Sent: Thursday, November 06, 2008 12:36 PM
To: isalist@xxxxxxxxxxxxx<mailto:isalist@xxxxxxxxxxxxx>
Subject: [isalist] Re: Strange Behaviour in ISA2006

Or, you wouldn't happen to have entered DNS servers on both the internal and 
external interface connections in Windows on the ISA Server would you?

Also, how do clients in your environment resolve internet-based DNS records?  
Are DNS forwarders set up on your internal DNS servers or are you using some 
other method for resolving internet-based DNS records?

Are the internal DNS servers part of the same internal network that your ISA 
Server sits on or do those internal queries pass through a router?

You can troubleshoot this by directing nslookup to use specific DNS servers for 
each record test case.

For example, if you wanted to query your internal DNS server for an external 
DNS record you could use:

nslookup www.yahoo.com<http://www.yahoo.com/><http://www.yahoo.com/> <Internal 
DNS Server>,

Where <Internal DNS Server> is the IP address of your internal DNS server.

To test against an external DNS server, you could use:

nslookup www.yahoo.com<http://www.yahoo.com/><http://www.yahoo.com/> <External 
DNS Server>,

Where <External DNS Server> is the IP address of an external DNS server your 
environment uses (usually one provided by your carrier/ISP).
On Thu, Nov 6, 2008 at 12:22 PM, Jim Harrison 
<Jim@xxxxxxxxxxxx<mailto:Jim@xxxxxxxxxxxx><mailto:Jim@xxxxxxxxxxxx<mailto:Jim@xxxxxxxxxxxx>>>
 wrote:
http://www.ISAserver.org<http://www.isaserver.org/><http://www.isaserver.org/>
-------------------------------------------------------

The combination of forward access and server login sluggishness point squarely 
at DNS.
Are you using the same DNS server to handle AD and external DNS queries?

Jim

-----Original Message-----
From: 
isalist-bounce@xxxxxxxxxxxxx<mailto:isalist-bounce@xxxxxxxxxxxxx><mailto:isalist-bounce@xxxxxxxxxxxxx<mailto:isalist-bounce@xxxxxxxxxxxxx>>
 
[mailto:isalist-bounce@xxxxxxxxxxxxx<mailto:isalist-bounce@xxxxxxxxxxxxx><mailto:isalist-bounce@xxxxxxxxxxxxx<mailto:isalist-bounce@xxxxxxxxxxxxx>>]
 On Behalf Of Ball, Dan
Sent: Thursday, November 06, 2008 8:30 AM
To: 
'isalist@xxxxxxxxxxxxx<mailto:isalist@xxxxxxxxxxxxx><mailto:isalist@xxxxxxxxxxxxx<mailto:isalist@xxxxxxxxxxxxx>>'
Subject: [isalist] Strange Behaviour in ISA2006

http://www.ISAserver.org<http://www.isaserver.org/><http://www.isaserver.org/>
-------------------------------------------------------

I've noticed an interesting behavior of my ISA2006 box, and was wondering if 
anyone would have an idea of what might be causing it...

Periodically, browsing to websites (from our Intranet) becomes sluggish and we 
experience a lot of time-outs, sometimes it clears itself, but sometimes it 
gets worse.  Tracing this back, it appears to be a DNS-related issue, the names 
cannot be resolved correctly.  I've restarted the internal DNS servers when 
this happens, with little, if any improvement in performance.  So I log into 
the ISA server via Remote Desktop to see what is happening, the login takes 
significantly longer than usual, then right about the time I get logged in, 
everything works perfect again, so I cannot trace it.

I thought it was a coincidence the first few times, but it has happened a 
couple of dozen times now and it is a definite pattern.  Once I log into the 
ISA server via Remote Desktop, it starts working again.  Any ideas?

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--
Cordially yours,
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Microsoft Certified Systems Engineer

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--
Cordially yours,
Jerry G. Young II
Microsoft Certified Systems Engineer



--
Cordially yours,
Jerry G. Young II
Microsoft Certified Systems Engineer

All mail to and from this domain is scrutinized by the Scrutinizer.
Follow-Ups:
- [isalist] Re: Strange Behaviour in ISA2006
  - From: Steve Moffat
References:
- [isalist] Re: Strange Behaviour in ISA2006
  - From: Ball, Dan
- [isalist] Re: Strange Behaviour in ISA2006
  - From: Steve Moffat
[isalist] Re: Strange Behaviour in ISA2006

Other related posts:
