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ATT DSL troubles with DNS

Posted on 2007-07-25
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Last Modified: 2008-01-09
Hello, We have posted about this issue before but have progressed forward and done some troubleshooting to try and isolate the issue.

Basic rundown of what our history is with this one client: They originally had ATT DSL running into the office with a Windows 2003 server. The problem is that DSL would cut out many times during the day for them on all machines. We did many thngs, like clean all the machines and install NOD32 on each one, redo the bad network wiring, update and secure the server, etc.

We had ATT put in a new line, entirely new run from outside, and the problem is still occurring. SO we had the ladies in the office perform the following tests via scripts off the desktop, and they gave us the results.

TEST 1: ping the router in office
TEST 2: ping the server
TEST 3: ping ATT DNS servers

The results are in, and while TEST 3 failed once or twice, now they tell us that all three tests work fine but internet still cannot be used - no web sites off any client machines can be reached.

We are going to have them run a tracert test to further see if we can isolate this issue when the internet drops out, but does anyone have any ideas as to what the culprit can be? THis ordeal has been a 2 month hell ride and we want to get down to the bottom of it.

DNS not configured right? ATT DNS not routing properly? Please any suggestions would be nice.
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Question by:FASTECHS
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by:Brugh
ID: 19567837
add TEST 4:  ping www.google.com

That will let you know if DNS is not working.

Is cable available in your area...that may be the easy fix.  :)
Just a personal note on that; I refuse to use DSL becuase of its antiquated protocols and slower speeds.   Its still techinically "dial up"

Have you tried replacing the Router/FIrewall to see if that could be the cause.

A tracert should definitely allow you too see where in the chain the link is broken, however, because its ICMP traffic, it's still difficult to say for sure as a lot of routers don't respond to ICMP.

 - Brugh



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by:knightrider2k2
ID: 19568084
what kind of router/firewall?
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by:FASTECHS
ID: 19568250
We will add the other test.

The router is the 2wire business modem/router solution from ATT which combines both functions. This is the second unit they are on - so yes, it has been changed.

Moving to Cable is our next step but we want to see if there are any last options for this quagmire.
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Expert Comment

by:knightrider2k2
ID: 19568474
>>now they tell us that all three tests work fine but internet still cannot be used - no web sites off any >>client machines can be reached

If this is true, then either it is a DNS problem or a Firewall problem. Check DNS first as Brugh mentioned. If the DNS is fine then check the firewall for any rules that could be blocking http/https. Also check if your firewall have any license limitations(number of concurrent connections) etc.
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by:FASTECHS
ID: 19568770
KINGHTRIDER:

the problem is sporadic - it happens at unknown times during the day with no rhyme or reason. If it was a firewall issue, the problem would be consistent throughout the entire day.

DNS def is having some issues and we are going to try and get it checked out with a fourth test to google.com.

Licensing used to be an issue and we thought this was the culprit, but they are a 6 person office using a 10 user Windows 2003 machine. Are there any other licensing issues that could have come about? We have a 10 CAL user license for 2003 server. If any more programs within Windows need to be licensed so they don't cut the net connection?
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Expert Comment

by:knightrider2k2
ID: 19570567
I was talking about Firewall/router licensing. Many firewalls have license limit on the number of concurrent connections. If there are  only 6 users then it is probably not a licensing issue.

>>Moving to Cable is our next step but we want to see if there are any last options for this quagmire

Changing to cable will not fix the problem if the problem lies somewhere else. I would first make sure it is a DSL problem before changing the ISP.

If all your tests are successfull(DNS, ping gateway, ping isp DNS), then it is probably your firewall/router or switch. Believe me, firewalls can be inconsistent.
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Author Comment

by:FASTECHS
ID: 19572013
We wanted to try a standalone router and modem (2 boxes instead of the one built in unit now by 2wire) and see if this fixes it. We will give this a go ahead.
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Author Comment

by:FASTECHS
ID: 19575184
And also, 2wire units are not standalone security appliances, which is what you're referring to.

I will post results from our next two tests as soon as we hear word back.
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Author Comment

by:FASTECHS
ID: 19577915
BIG UPDATE FOR THIS PROBLEM:

So I went over to the clients today to see what was going on and to try and put the fourth test onto the client systems. THE INTERNET goes out as soon as I arrive, so I start troubleshooting on my own and here is what I find:

- When the net went out, no one could access the net. Server or clients. Server handles DNS. All clients use server for DNS.
- I tried to ping the router from the server - COULD NOT
- tried to ping the router from the clients - WORKED
- Was curious, so I changed over DNS on two clients to use ATT direct DNS. INTERNET WORKS FINE. Server still cant get on net, and the third client that wasnt changed over cannot either.
- During the entire outage, the above was true.

Does anyone know what this tells me? Is DNS on the server screwed up and causing the net requests to drop ever so often? Whats the rhyme or reason behind this?
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Expert Comment

by:knightrider2k2
ID: 19595319
That explains why internet is not working. I think the culprit is the NIC on the server but check the following
Check network settings on the server's NIC.
Try changing the Port on the switch on which the server is connected.
Try installing a new NIC on the server.
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Expert Comment

by:knightrider2k2
ID: 19595326
Sorry I forgot

Try changing the network cable between the server and the switch
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Author Comment

by:FASTECHS
ID: 19610890
Will try the above solution. You don't think it could be a bad DNS settings on the server itself?
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Author Comment

by:FASTECHS
ID: 19620643
OK

1) We installed an alternate NIC by Linksys (Gigabit EG1032v2 card) and it works fine. However I could not test the connection on the clients using the server for DNS. I will get word from the office on what happens tomorrow or early next week.
2) Could someone tell us if the following screenshots of the DNS manager look correct, in specific, the two forward lookup zones we have? Is this normal?

http://xs218.xs.to/xs218/07314/dns_1.jpg
http://xs218.xs.to/xs218/07314/dns_2.jpg
http://xs218.xs.to/xs218/07314/dns_3.jpg
http://xs218.xs.to/xs218/07314/dns_4.jpg

Please let us know,especially if you have worked extensively with Server 2003. If this isnt correct, tell us please how to resolve. AGAIN, clients using DNS from ATT directly are OK with internet access but the one machine with DNS routing from Server first is still having troubles!
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Author Comment

by:FASTECHS
ID: 19629107
We also ended up switching out their 2wire business gateway for a standalone Creative Briteport modem and a standalone BEFSR81 8 port Linksys router. We are going to see how this in combination with the new NIC card for the server stands up.
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Accepted Solution

by:
knightrider2k2 earned 1500 total points
ID: 19647378
These screenshots does not give any detail about the functioning of the DNS server. check this out
http://www.petri.co.il/install_and_configure_windows_2003_dns_server.htm

Make sure that in the NIC's propertires, the DNS server is pointed to itself.
Make sure you have forwarders setted up correctly. ( use att dns server as forwarders)
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