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Can't access specific websites

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Can't access specific websites - 13.Apr.2010 6:09:48 AM   
elliot

 

Posts: 24
Joined: 22.Apr.2009
Status: offline
Hi there,

We have 2 DNS Servers in our domain and 1 ISA Server 2006. The issue is that from time to time (almost always) users can't access some websites (specifically microsoft.com) and IE returns a page:

X Network Access Message: The website cannot be found
Explanation: The IP address for the website you requested could not be found

Technical Information (for support personnel)
Error Code 11001: Host not found
Background: This error indicates that the gateway could not find the IP address of the website you are trying to access. This is usually due to a DNS-related error.
Date: 4/13/2010 10:02:20 AM [GMT]
Server: <FQDN of the ISA Server>
Source: DNS error

Any idea?

Best Regards,
Elliot Nehme
Post #: 1
RE: Can't access specific websites - 13.Apr.2010 6:24:41 AM   
Jason Jones

 

Posts: 4663
Joined: 30.Jul.2002
From: United Kingdom
Status: offline
How is DNS configured on ISA?

_____________________________

Jason Jones | Forefront MVP | Silversands Ltd
My Blogs: http://blog.msedge.org.uk/ and http://blog.msfirewall.org.uk/

(in reply to elliot)
Post #: 2
RE: Can't access specific websites - 13.Apr.2010 6:29:18 AM   
elliot

 

Posts: 24
Joined: 22.Apr.2009
Status: offline
Hi Jason,

What do u mean by how the DNS is configured on ISA?
We don't have any special configuration on ISA server for the DNS.
Should i configure something on it? Eventhough all websites are accessible by the users except microsoft.com and a couple of other websites

Best Regards,
Elliot Nehme

(in reply to Jason Jones)
Post #: 3
RE: Can't access specific websites - 13.Apr.2010 6:43:42 AM   
Jatin.Jagota

 

Posts: 25
Joined: 21.Aug.2008
Status: offline
Go in ISA Server > Configuration > General > Define HTTP Compression Preferences > [Check] Enable HTTP compression.

Hope this should work.

Regards,
JJ

(in reply to elliot)
Post #: 4
RE: Can't access specific websites - 13.Apr.2010 7:07:49 AM   
elliot

 

Posts: 24
Joined: 22.Apr.2009
Status: offline
Hi Jatin,

The Enable HTTP compression is already checked and still can't access microsoft.com

Best Regards,
Elliot Nehme

(in reply to Jatin.Jagota)
Post #: 5
RE: Can't access specific websites - 13.Apr.2010 7:12:58 AM   
elliot

 

Posts: 24
Joined: 22.Apr.2009
Status: offline
PS. I even can't ping microsoft.com from command prompt (Request time out) while i can ping any other website

Best Regards,
Elliot Nehme

(in reply to elliot)
Post #: 6
RE: Can't access specific websites - 13.Apr.2010 7:14:10 AM   
Jatin.Jagota

 

Posts: 25
Joined: 21.Aug.2008
Status: offline
try to give universal DNS in your ISA External Traffic NIC:

Primary DNS: 4.2.2.2
Alternate DNS: 4.2.2.1

(in reply to elliot)
Post #: 7
RE: Can't access specific websites - 13.Apr.2010 7:20:08 AM   
Jatin.Jagota

 

Posts: 25
Joined: 21.Aug.2008
Status: offline
also, try to clear the local ISA Cache from the Cache console and after that try to clear the NIC cache from below given command:

IPCONFIG /Flushdns

IPconfig/registerdns.

I hope this will work

(in reply to Jatin.Jagota)
Post #: 8
RE: Can't access specific websites - 13.Apr.2010 7:24:34 AM   
Jatin.Jagota

 

Posts: 25
Joined: 21.Aug.2008
Status: offline
Also, if again this won't work, please check is there any entry against the name of microsoft.com in the ISA server local host file on the below given path:

c:\WINDOWS\system32\drivers\etc\hosts

If yes, clear that entry and save the file.

Regards,
JJ

(in reply to Jatin.Jagota)
Post #: 9
RE: Can't access specific websites - 13.Apr.2010 7:30:54 AM   
elliot

 

Posts: 24
Joined: 22.Apr.2009
Status: offline
Changed the external NIC DNS to universal ones... did the command in command prompt...but still :S

(in reply to Jatin.Jagota)
Post #: 10
RE: Can't access specific websites - 13.Apr.2010 7:51:08 AM   
Jatin.Jagota

 

Posts: 25
Joined: 21.Aug.2008
Status: offline
Elliot,

Have you checked the alerts tab in ISA console? is there any alert coming when you are hitting microsoft.com?

If yes, that statement will contain the resolution for it in the alert only.

Also, check that when you use internet without using ISA server as proxy in internet explorer, will microsoft.com open?

If no, this can be a ISP related issue.

Also, you can check by installing WireShark on the ISA server, and can monitor the microsoft.com response, and also it will show you that where on your network it is getting blocked.

(in reply to elliot)
Post #: 11
RE: Can't access specific websites - 13.Apr.2010 8:05:22 AM   
Jatin.Jagota

 

Posts: 25
Joined: 21.Aug.2008
Status: offline
Elliot,

also, try the given steps on below thread:

http://forums.isaserver.org/m_2002017583/mpage_1/key_/tm.htm#2002017583

Regards,
JJ

(in reply to Jatin.Jagota)
Post #: 12
RE: Can't access specific websites - 13.Apr.2010 8:11:28 AM   
paulo.oliveira

 

Posts: 3472
Joined: 3.Jan.2008
From: Amazon, Brazil
Status: offline
Hi,

check if your ISA NICs are configured properly: http://blog.msfirewall.org.uk/2008/06/isa-servers-recommeded-network-card.html

Regards,
Paulo Oliveira.

_____________________________

Microsoft Premier Field Engineer (PFE)
Blog: http://poliveirasilva.wordpress.com/
Twitter: https://twitter.com/poliveirasilva

(in reply to elliot)
Post #: 13

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