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James HilloyaFlag for Costa Rica

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Very Frustrating! is it a DNS Problem??? Please help

Hello, I am having a very annoying problem with my Windows 2003 server Domain Controller/DNS Server/DHCP Server (same machine does all this).....it boots up fine, no errors in event viewer, all clients authenticate fine and can access the internet fine. However, every 5 or 6 hours, all clients and the server lose "partial" internet connectivity. I say partial because even though clients cannot browse the Internet ( they get the "this page cannot be displayed" message in their browser),their msn messengers (if they were logged in to msn messenger) still work, they can still chat with their contacts...it is weird...they don't get disconnected from msn messenger but when they go to a website using either IE or Firefox they cannot browse the net, it's like if they were offline for browsing websites....would this mean that maybe a port is being blocked? port 80 maybe?? ..

 If I reboot the Domain Controller they can browse again the internet fine with no problems for another few hours until it happens again...is this  a DNS problem?? There are no error in event viewer...Should I check or test something?? Please help...
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AdamRobinson

Out of curiosity: Can they still view pages that they've already browsed before the "internet connectivity" goes out?

Are you going through a proxy server?

Is there an external firewall device through which traffic is routed?

While internet is not working can you do telnet Servername:port no(80) and check whether you are able to connect to it. If it is not able to connect to it then there is some problem and port 80 is being blocked. Do this test also at the same. If port 80 is getting blocked, then change the IP of system you are testing and do the telnet test. Check whether you are able to connect. If yes then check IIS settings on your DC whether any IP's getting blocked.

Give the test results so that we can debug
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Yes they can still browse pages that are stored in their cache..but if they try to go to a new web page, they get the "this page cannot be displayed" message...all clients lose the ability to browse pages, just as if there was no internet...We do not use a proxy server and there is no external firewall...........everything was working fine until last week when we have a black out...I am not sure if that had anything to do with it but i figured i would post it here anyway..the DC is on a ups and it has always been...we've had this issue for a week now.......any suggestions?? do u think  this is a DNS issue??...I have not instaled or changed anything in the server at all, the only thing that has happened was the blackout but i don't see how that would create this particular issue....:-(
Is the DHCP Gateway pointing to the router?
Is the DNS pointing to the server IP?
Have you installed WINS?
inbarasan I did did just now while we DO have internet,,,..i went to a command prompt on the server and on a client machine with the same results...( servername is cvddc )

C:\Documents and Settings\cvdadmin94.CONCEPTRONIC>telnet cvddc:80
Connecting To cvddc:80...Could not open connection to the host, on port 23: Conn
ect failed

C:\Documents and Settings\cvdadmin94.CONCEPTRONIC>


Port 23??? where did that come from???
If I go to the servers TCP IP properties, the preferred dns server option has the ip for the server itself....
wins is not installed...it never has been installed and it has been ...
umm i think i have a brain fart..where so i check to see if the dhcp  gateway is pointing to the router??...i went to the dhcp server options, did i right click and selected configure options....none of the available options are selected..
sorry, I meant WINS is not installed on the server and it never has been...

where do i check to see if the dhcp  gateway is pointing to the router??...i went to the dhcp server options, did a right click and selected "configure options"....none of the available options are selected....ummm is this my problem??
Are you using proxy to connect to internet,if you are not using proxy server, then you will using your DNS for resolving external DNS name. You need to check that. Probably if you know your ISP DNS Address then use that as Forwarder in your DNS Server.
I am not using a proxy to connect to the Internet.....how do i check if i am using dns for resolving external dns names?...

if I go to my  DNS Management and I do a right click on the server, I select properties and in the forwarders tab the only thing I see is "All other domains". This is under DNS DOmain..........do i need to add in here my isps' dns ip's?
To check the DHCP and Gateway...from the cmd prompt type ipconfig /all
Glenn, the DHCP points to itself since the server is the dhcp server also....and the gateway points to the router
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inbarasan
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inbarasan I did that, do I need to add anything under forwarders also?? or leave it blank?
inbarasan, when i tried to add the 2 ip's of my isp's dns servers right below all other domains, I get an error that say "Each forwarder must be configured with one or more master DNS Server IP Addresses. Provide a Master DNS Server IP Address for the domain 65.xxx.x.xxx"

Gentlemen I am now getting DNS errors in the event viewer, errors are 4004 and 4015 source =DNS...any suggestions? Thanks