All Windows 7, Vista, and Server 2008 systems cannot view certain websites from inside our domain. The XP and Server 2003 systems however can access these websites without issue. We are currently running a Server 2008 R2 Domain Controller with DNS, DHCP, Etc. I have checked Antivirus, Firewalls, and Filtering. I have tried pointing to different DNS servers from my internal to a public and it makes no difference. I have checked updates/security updates and none have been installed between the time it worked and now fails to work. Example of failed sites: http://kixtart.org http://owotw.com If anyone has any information that may help to resolve this it would be extremely helpful!

This could be EDNS0 related. If on your DNS servers, you configure them to forward to other DNS systems, such as those provided by your ISP, do you still have this issue? If issue is resolved, most likely EDNS0 related. The most appropriate fix is to update your perimeter firewall but other work-arounds are available. Read more.. http://itgeared.com/1146-windows-server-2008-r2-dns-issues-edns0 Guides and tutorials, visit ITGeared.com.

Hello Jorge, Thank you for the response, I had not heard of this previously and I did recently upgrade to Server 2008 R2. I made the changes the article suggested but it has made no difference to the issue, I still cannot browse those sites. The Firewall currently in use is an old Cisco PIX 515E, nothing has changed on it in years. I do want to replace it, but this will have to wait until a break where there is significant downtime. Any other suggestions?

Nslookup of kixtart.org indicates it resolves to IPv4 & IPv6 addresses. You could try disabling IPv6 on a Win 7 machine & testing to see if this is causing the problem. To disable IPv6... http://support.microsoft.com/kb/929852Douks

Hi Douks, Thank you for your reply, I have all IPV6 currently disabled in the network, all workstations and servers. I did notice that the PIX 515E has old software and is incapable of allowing enhanced packets or increased packet sizes. I don't know if this is where the problem is. I have setup forwarding and it made no difference along with changing the DNS on the Win7 workstations to public DNS. The websites are still failing to load. I can however resolve them fine through nslookup. Any other ideas?

In case the issue is browser related, what are you using & have you tried alternatives?Douks

Hi, Also, Have you tried to directly connect these computer to Internet? According to your description, it seems that the filter server blocks packages between these websites and your domain.Juke Chou TechNet Community Support

This should not be a browser issue either, i just tried openning this links on my windows 7 enterprise with IE 9 and it worked. Try disabling UAC. Try updating your flash player. Here what they recomand that needs to be enabled. Topic Minimum Recommendation Notes Processor Pentium® 1GHz We recommend Pentium 1.5 GHz or faster. Memory 1 GB RAM We recommend 2 GB or greater. Disk Space 4 GB free space Video RAM 128 MB graphics memory Operating System Windows XP Windows Vista® Windows 7 Mac OS X 10.5+ Ubuntu® 9.x+ For a Windows XP installation, your installation must include Service Pack 3 (SP3). Browser Mozilla Firefox® 3.6.x Microsoft Internet Explorer® 7 or higher Safari® 4+ JavaScript™ Enabled This setting is the default of most installations. Multimedia Rendering Adobe® Flash® 8.x or higher PDF Reader Adobe® Reader 9.x Reports are generated as a PDF file. Caching Enabled This setting is the default of most installations. Cookies Enabled This setting is the default of most installations. Screen Resolution 1024 x 768 or larger Optional

I am having the same exact issue. Windows 7 workstations cannot view some websites such as firefox.com or mozilla.org but windows xp does not have any issues at all. If any of the windows 7 laptops are outside the network they do not have any issues at all. We are running a Pix 515 with old software. Has anybody found a definite answer to this issue? Thanx.