Solved

I can't get out to a specific website

Posted on 2011-02-10
9
384 Views
Last Modified: 2012-05-11
Integrated Active Directory DNS 2003

We have a specific website we can't access from our internal network, but it can be accessed from outside of our network. It's not a web filter issue, it's a dns issue. If I use our internal DNS servers it doesn't work, but if I put in a static DNS like 4.2.2.2, then I can get to the site.

I need some ideas, on how to resolve this DNS issue...
0
Comment
Question by:bernardb
  • 5
  • 3
9 Comments
 
LVL 70

Expert Comment

by:Chris Dent
Comment Utility
Using Forwarders or Root Hints? Root Hints is the default, but if you're not sure, pop open the Properties for your DNS server then select the Forwarders tab.

Perhaps the most common cause of obscure resolution failure is EDNS (Extended DNS). This happens because some routers / firewalls silently drop UDP packets larger than 512 bytes. EDNS is a change that means the server advertises support for packets over 512 bytes, if the network hardware doesn't support that as well you end up with trouble.

To test if this is the case, run:

dnscmd /config /EnableEDnsProbes 0

This disabled EDNS, once done, flush the cache with:

dnscmd /ClearCache

Then run:

nslookup www.TheSiteThatFailedBefore.com

Chris
0
 

Author Comment

by:bernardb
Comment Utility
Here's another piece....

I can get to www.blah.org

but not www.blah.org/dev

internally it doesn't work, but externally from outside of our network I can. it's on the same server etc.
0
 

Author Comment

by:bernardb
Comment Utility
and the error is 'HTTP 404 - File not found
Internet Explorer'
0
 
LVL 70

Expert Comment

by:Chris Dent
Comment Utility

That takes it out of the hands of DNS.

If you couldn't get to www.blah.org, but could to bob.blah.org we could blame DNS. But if it's a sub-directory under a website DNS is done before you get to the /dev bit.

Chris
0
Why You Should Analyze Threat Actor TTPs

After years of analyzing threat actor behavior, it’s become clear that at any given time there are specific tactics, techniques, and procedures (TTPs) that are particularly prevalent. By analyzing and understanding these TTPs, you can dramatically enhance your security program.

 
LVL 70

Expert Comment

by:Chris Dent
Comment Utility

> and the error is 'HTTP 404 - File not found ...

Even better, the only thing that can return that is the remote web server. Now you ruled out both DNS and the network layer.

Either the web server is wrong, or we swing back and wonder if you're getting the same answer. Fortunately we can check that:

nslookup www.blah.org
nslookup www.blah.org 8.8.8.8

The first asks your internal DNS server, the second Google's DNS server. Both should return the same thing in almost all cases.

Chris
0
 
LVL 4

Expert Comment

by:evgeny_f31
Comment Utility
if I put in a static DNS like 4.2.2.2, then I can get to the site
Does it work if you use 4.2.2.2 as dns forwarder address ?
How exactly your network gets the internet - routers, proxy  ?
0
 

Author Comment

by:bernardb
Comment Utility
Chris-Dent
They return different IP addresses when I tried

nslookup www.blah.org
nslookup www.blah.org 8.8.8.8

The first asks your internal DNS server, the second Google's DNS server. Both should return the same thing in almost all cases.
0
 

Accepted Solution

by:
bernardb earned 0 total points
Comment Utility
Thanks Everyone.

The issue was we had an A record on our DNS server that pointed to www.blah.org's old internet service provider.

I removed the A record
0
 

Author Closing Comment

by:bernardb
Comment Utility
Resolved by me, but thanks to all. You Experts are the best.
0

Featured Post

How to improve team productivity

Quip adds documents, spreadsheets, and tasklists to your Slack experience
- Elevate ideas to Quip docs
- Share Quip docs in Slack
- Get notified of changes to your docs
- Available on iOS/Android/Desktop/Web
- Online/Offline

Join & Write a Comment

This article explains how a domain name may be inadvertently appended to all DNS queries. This exhibits as described below. (CODE)And / Or: (CODE) Cause This issue can occur in either of these two scenarios. EITHER 1. A Primary DNS S…
I've written instructions for one router type, but this principle may be useful for others of the same brand and even other brands of router. Problem: I had an issue especially with mobile devices that refused to use DNS information supplied via…
Excel styles will make formatting consistent and let you apply and change formatting faster. In this tutorial, you'll learn how to use Excel's built-in styles, how to modify styles, and how to create your own. You'll also learn how to use your custo…
This video gives you a great overview about bandwidth monitoring with SNMP and WMI with our network monitoring solution PRTG Network Monitor (https://www.paessler.com/prtg). If you're looking for how to monitor bandwidth using netflow or packet s…

763 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question

Need Help in Real-Time?

Connect with top rated Experts

7 Experts available now in Live!

Get 1:1 Help Now