website dns routing not resolving from a web browser

35 pts.
Tags:
DNS
Domain
Networking
Routing
Hi, I've got a network domain called myDomain.co.uk and also a website called www.myDomain.co.uk. Problem is I can't see my website from within my network domain (but I can from outside). I tried setting up a DNS host for "www" that resolved to the correct address (not an elegant solution!) which seemed to work for a while, but has now stopped. If I ping/tracert the address, it routes out of the door and resolves to correct address. But from a browser, it just comes back with "page cannot be displayed". Can anyone point me in the right direction?

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It sounds like you may have a name resolution issue. In other words, when you are outside your “home” network your DNS server will resolve the www.mydomain.co.uk address. When you are inside the “home” network it will not. You likely have different DNS servers performing name resolution depending on where you are located. The home DNS server does not have an A record for the www host or does not know how to forward a request to a server that does know the www host.

Another thing to check is your browser cache. Make sure it is cleared and refresh the page. See if the page not found error is cleared that way. Are you using a proxy server inside the “home” network? If so, make sure it can resolve the www name. What happens if you telnet to port 80 on the www host from inside the “home” network? What happens if you put in the ip address of the www host in the browser rather than the DNS name?

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check your firewall/router. Maybe you have a rule blocking access from the outside when the source is on the same network or on the inside? Can you configure a host file to access the web from the inside interface? Do you have a proxy? If so, do you have a rule in place for local LAT or your own public address space?
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  • F2F
    Hi, thanks for that. I've taken out the addtional DNS servers referenced on my PDC server, so now I only have one - the server itself. This should make the problem less confusing, at least. I can still see the web etc as normal, but still not the www.myDomain.co.uk site. I have an A record set to be "www" which points to the correct IP address. (as mentioned previously, this crude method used to work - presumable because it'll append the domain's ".myDomain.co.uk" to the "www" prefix and everything then resolves correctly. It's definitely not browser cache - I've tried that. I don't have a proxy, I route straight out through the gateway. If I try and browse the IP address, I get the same error. If I try and telnet on port 80 I fail to connect. The firewall has no rules to block the site, ports or traffic in the ways that you've described. You mentioned forwarding the request on - I've seen that sort of thing on firewalls (where you allow traffic access and then forward it on to a specific IP address), but how does that work on a server, as it sounds like that might be the right way to go? Thanks.
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  • Labnuke99
    A firewall somewhere must be blocking your outbound traffic to port 80 for that IP address. The situation you describe indicates that there is something blocking port 80 traffic between your network and the destination server.
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  • Petecee
    Hi, Have you checked you haven't got a root zone "." in your DNS Forward Lookup Zones. If it is there delete it and try again, you may have to Control F5 to refresh the page.
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  • F2F
    Hi again, Thanks for all your input. I've added a specific firewall rule to allow inbound/outbound traffic to/from the address and given it priority. The issue still persists, unfortunately. I've also checked my root zones for the entry mentioned. I can't see one. The browser errors that I get do seem to be pointing towards a DNS issue. Is it something along the lines of addresses resolving to "myDomain.co.uk.myDomain.co.uk" - rather than just the www.myDomain.co.uk which is why it's failing? Because the domainname is being appended by default? The only address that fails is the one named the same as the domain Name suffix. Thanks.
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  • Labnuke99
    Did you try to telnet to port 80 on the specified IP address of the destination webserver? This will confirm if your firewall rule is working or not. Try also opening ICMP and do a tracert to the destination server to see where the packets may be reaching but not coming back.
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  • F2F
    Hi, I tried the telnet and had the firewall log the connection - it was definitely routed through ok as it showed on the log as accepted. I've done a ping and a tracert from the firewall and from behind the firewall directly and both reply/resolve to the correct IP outside of the network. This is the only website address that we can't see - I've temporarily switched off any blocking on our firewall to confirm this. Thanks.
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