Question

Site resolves but does not connect

Asked by: vsmusic2000

Hi Experts,
I have a certain external website that resolves by my DNS but http traffic does not reach there. I think its something to do with my proxy server. When I tried to use my ISP's proxy server, it connected.
I am getting an error Error Code 11002: Host not found.
So I am pretty sure that there is something in my proxy that is not allowing it but I cant seem to figure out what it could be.
Please help experts.

This Question has been solved and asker verified All Experts Exchange premium technology solutions are available to subscription members.

Subscribe now for full access to Experts Exchange and get

Instant Access to this Solution

  • Plus...
  • 30 Day FREE access, no risk, no obligation
  • Collaborate with the world's top tech experts
  • Unlimited access to our exclusive solution database
  • Never be left without tech help again

Subscribe Now

Asked On
2009-09-23 at 22:08:12ID24757374
Topics

Network Management

,

MS Forefront-ISA

Participating Experts
3
Points
500
Comments
15

Trusted by hundreds of thousands everyday for fast, accurate and reliable tech support.

  • "The time we save is the biggest benefit of Experts Exchange to Warner Bros. What could take multiple guys 2 hours or more each to find is accessed in around 15 minutes on Experts Exchange." Mike Kapnisakis, Warner Bros.
  • "Our team likes having a resource that is more secure than just using Google and most experts using this service really know their stuff. It's nice to look here first versus using Google." Dayna Sellner, Lockheed Martin
  • "Anytime that I've been stumped with a problem, 9 out of 10 times Experts Exchange has either the accepted solution or an open discussion of the potential solution to the problem." Kenny Red, eBay Inc.

See what Experts Exchange can do for you.

Got a question?

We've got the answer.

Experts Exchange has been collecting answers to technology questions since 1996…3 million and counting! If you have a question, chances are we already have your answer.

Screenshot of Experts Exchange Knowledgebase

Need individual assistance?

Our experts are ready to help.

If you can't find the exact answer you're looking for, ask our exclusive community of 50,000 experts. You’ll get a personalized answer from a trusted professional.

Screenshot of Experts Exchange Knowledgebase

Want to learn from the best?

Read articles from industry experts.

Thousands of free tech tips, tricks, how-to’s and tutorials are available in our peer reviewed articles section. See for yourself how smart our experts are, no login required.

Screenshot of an Article

Working on a long term project?

Store your work and research.

Save solutions to your questions, answers you’ve discovered through searching plus helpful articles in your personal knowledgebase for easy future access.

Screenshot of Experts Exchange Knowledgebase

Access the answers to your technology questions today.

Subscribe Now

30-day free trial. Register in 60 seconds.

What Makes Experts Exchange Unique?

Members of the expert community talk about why the experience at Experts Exchange is different than what you will find anywhere else.

Trusted by the world's most respected brands.

image of each brand's logo

Faithfully serving IT professionals since 1996.

Experts Exchange Logo

Try it out and discover for yourself.

Subscribe Now

30-day free trial. Register in 60 seconds.

Related Solutions

  1. proxies
    how come when i try to use a proxy to surf the web i get a message saying the page could not be displayed?
  2. ISP DNS Resolver Issue
    We just switched our ISP to ATT and for some reason were are unable to access certain websites. We get page cannot be displayed. I cannot even ping the sites. Yet other pages work fine. If I use our backup ISP (local cable company) I can get to the pages. I have called s...

Free Tech Articles

  1. WARNING: 5 Reasons why you should NEVER fix a computer for free.
    It is in our nature to love the puzzle. We are obsessed. The lot of us. We love puzzles. We love the challenge. We thrive on finding the answer. We hate disarray. It bothers us deep in our soul. W...
  2. SCCM OSD Basic troubleshooting
    SCCM 2007 OSD is a fantastic way to deploy operating systems, however, like most things SCCM issues can sometimes be difficult to resolve due to the sheer volume of logs to sift through and the dispe...
  3. Migrate Small Business Server 2003 to Exchange 2010 and Windows 2008 R2
    This guide is intended to provide step by step instructions on how to migrate from Small Business Server 2003 to Windows 2008 R2 with Exchange 2010. For this migration to work you will need the fo...
  4. Create a Win7 Gadget
    This article shows you how to create a simple "Gadget" -- a sort of mini-application supported by Windows 7 and Vista. Gadgets can be dropped anywhere on the desktop to provide instant information, ...
  5. Outlook continually prompting for username and password
    There have been a lot of questions recently regarding Outlook prompting for a username and password whilst using Exchange 2007. There are a few reasons why this would happen and I will try to cover t...
  6. Backup Exchange 2010 Information Store using Windows Backup
    There seems to be quite a lot of confusion around the ability to backup Exchange 2010 using the built in Windows Backup feature. This stems from the omission of this feature prior to Exchange 2007 s...

Cloud Class Webinars

  1. Avoiding Bugs in Microsoft Access
    Alison Balter takes and in-depth look at avoiding bugs in Access. In this webinar you will learn about using the immediate window to debug your applications, invoking the debugger, using breakpoints to troubleshoot, stepping through code, setting the next statement to execute, ...
  2. Top 10 Best New Features in Visio 2010
    Scott Helmers gives live demonstrations of the top 10 new features in Visio 2010. This webinar will teach you how to create compelling diagrams by adding shapes to the page with a single click, linking the shapes in a diagram to data in Excel (or SQL Server, or SharePoint), ...
  3. IT Consultant Business Secrets Revealed
    Michael Munger, Experts Exchange tech pro and IT consultant, pulls back the curtain on his very successful businesses and answers question on every IT consultant and business owner should know about. He shares secrets on what he did to solve the 5 most common problems in IT, ...
  4. Disaster Recovery and Business Continuity
    Quest CTO, Mike Billon, gives an overview of the steps involved in building a dunamic disaster recovery plan. Through case studies and an examination of software/hardware tooles for monitoring and testing, you'll gain a better understandin of where you are, where you want ...
  5. Organize Your Visio Diagrams with Containers and Lists
    Scott Helmers uses cross functional flowcharts, wireframe diagrams, data graphic legends and seating charts to teach you: how to ustilize all three new structured diagram components in Visio 2010, the best practices for organizeing shapes in previous version of Visio, how to organize ...
  6. How to Us Objects, Properties, Events and Methods in Microsoft Access
    Alison Dalter gives an in-depbth look at objects, properties, events and methods in Microsoft Access. In this webinar you will learn about using the object browser, referring to objects, working with properties and methods, working with object variables, understanding the ...

Join the Community

Give a Little. Get a Lot.

Join the community of experts here and help other tech pros by answering question in your area of expertise. You can earn FREE access to all Experts Exchange's premium features and resources.

Join the Community

Answers

 

by: arnoldPosted on 2009-09-23 at 22:30:33ID: 25410310

Are you using a reverse proxy?  Your issue might be the internal device tries to access an external resource that is mapped on the router to another internal device.
Often this is a feature that is enabled to prevent spoof/storms.

On the router web server public IP port is mapped to internal LAN ip port

Your internal proxy is trying to access public IP port, but the router does not allow the traffic from the inside to go out the external interface and then come back in.
One option is to maintain an internal DNS record for the external domain such that www.yourdomain.com internally points to the internal LAN IP while the external DNS record for www.yourdomain.com points to the public IP.
It requires additional management/record maintenance.

 

by: ahmedabdelbasetPosted on 2009-09-24 at 00:33:43ID: 25410770

On ISA , allow the URL site or domain sets that ISA may block it

http://www.isaserver.org/articles/2004firewallblocklist.html

 

by: vsmusic2000Posted on 2009-09-24 at 00:42:03ID: 25410811

We tried giving the primary DNS for the ISA as our internal DNS server and the external as our ISP DNS server. but then we started getting another problem where the ISA kept asking for login credentials when trying to access any sites on the internet.
When we removed the secondary DNS (the ISP DNS), then it was fine but this site was again not accessible.
This site is not blocked and is in the allow list, so there is no rule blocking it. It just does not 'find' the host or server for http traffic. We are using ISA 2006.

 

by: ahmedabdelbasetPosted on 2009-09-24 at 00:43:28ID: 25410823

on ISA , create host file for External domain .

 

by: vsmusic2000Posted on 2009-09-24 at 00:45:42ID: 25410839

Hi Ahmed,
it resolves the IP of the server but cannot connect via http through the proxy. So adding into the hosts file would not help. Actually I have tried that too, but resolving is not the issue. I hope I am clear on this.

 

by: ahmedabdelbasetPosted on 2009-09-24 at 01:15:58ID: 25410985

Could you open this site on ISA it self ?


 

by: vsmusic2000Posted on 2009-09-24 at 05:11:28ID: 25412386

Nope, the ISA is also using itself to get to the internet. Our firewall blocks direct http traffic and internet would only work when proxy is used.

 

by: Kumar_Jayant123Posted on 2009-09-24 at 12:55:30ID: 25417154

One question... Do you have any other proxy server other then ISA??

You said that Firewall will Block direct access to the internet and allow if only proxy is used..

Thanks
Kumar

 

by: vsmusic2000Posted on 2009-09-27 at 02:38:06ID: 25433322

There is only one Proxy server. People who try and use the internet without the proxy server or use any other proxy address would not be able to connect to the internet as the direct access to the internet without passing through the proxy is blocked.

 

by: arnoldPosted on 2009-09-27 at 08:49:48ID: 25434278

Is the ISA also the proxy?

 

by: vsmusic2000Posted on 2009-09-27 at 21:35:03ID: 25436755

Yes, it is.

 

by: arnoldPosted on 2009-09-28 at 07:36:33ID: 25439703

This is an issue within your configuration.  Could you check the ISA as well as the proxy logs to see what happens when access from the inside is attempted for the website.
I suspect the ISA is not letting the traffic backin.

 

by: vsmusic2000Posted on 2009-10-01 at 19:16:10ID: 25474783

I will check that and come back with the observation.

 

by: vsmusic2000Posted on 2009-12-29 at 21:00:06ID: 31632834

Even though the site was not in the blocked list, by adding it explicitly in the allowed list, it worked.

20120131-EE-VQP-002

3 Ways to Join

30-Day Free Trial

The Experts

98% positive feedback on 31,087 answers since March 2000. angeliii is a Microsoft Most Valuable Professional for his work with MS SQL Server & Develoment.

He has also proven his knowledge of Visual Basic Programming, PHP Scripting and Oracle Databases.

The Experts

97% positive feedback on 10,752 answers since July 2000. lrmoore has more than 18 years experience in the networking industry.

The six-time Mircosoft MVPs specialties include firewalls, virtual private networking, and network management.

Testimonials

"...and excellent source for support... Kind of like having your very own IT dept." Electriciansnet

Testimonials

"I was apprehensive at signing up at first. However... it has already made my life as an IT administrator much easier." JaCrews

Testimonials

"WOW! You guys have great, active, and knowledgeable people on here." moore50

Business Clients

Business Clients

In the Press

"If you’ve got a question... Experts Exchange can supply an answer.”

In the Press

"...an invaluable aid for both IT professionals and those who require tech support."

In the Press

"where IT professionals provide quick answers on just about any topic"

Business Account Plans

Loading Advertisement...