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DNS problems

waldron
Grafter
Posts: 348
Registered: 28-07-2007

DNS problems

For the past three months or so I have been experiencing occasional problems. I can be using IE8 or Firefox successfully for some time, then suddenly I can no longer access any web pages. Windows Mail and other applications already loaded are still OK, but I can't access the internet with any newly loaded programs.
Windows Live Messenger won't load, and it's troubleshooter fails on the DNS check. I've tried changing the DNS settings to use OpenDNS, but the failures still occur.
Although it has happened at different times of the day, the majority have been between 18:00 and 19:30 although I don't think I have had more than one on any day. The latest was at 19:10 today. The only solution seems to be to restart the router each time.
13 REPLIES
Community Gaffer
Community Gaffer
Posts: 13,161
Thanks: 928
Fixes: 77
Registered: 04-04-2007

Re: DNS problems

Sounds to me like your router could be on the blink. Might be worth resetting it to factory defaults and reconfiguring it. Have you got access to another modem or router that you could try?

Bob Pullen
Plusnet Product Team
If I've been helpful then please give thanks ⤵

waldron
Grafter
Posts: 348
Registered: 28-07-2007

Re: DNS problems

Bob. I don't understand why you suspect the router to be at fault. Programs already active, such as Windows Mail, X-Lite and Windows Live Messenger carry on running successfully. It is only IE8 or Firefox going to a new site (ie new IP address) which fail. If I then close Messenger and attempt to reload it, it also fails and it's Troubleshooter points to a DNS failure.
Community Gaffer
Community Gaffer
Posts: 13,161
Thanks: 928
Fixes: 77
Registered: 04-04-2007

Re: DNS problems

Stranger things have happened.
If DNS resolution was up the creek then you probably wouldn't be able to do anything. A quick test would be to try browsing to a website by its IP the next time you have problems. Try something like Google at http://216.239.59.104/ - If that fails to load then you're looking at a browser issue or something that's interfering with your routing/network connectivity and not a DNS issue. Are you running a software firewall on your PC?
The reason I ask if you've access to any alternative kit is so that it can be ruled out at an early stage. The last thing you want to do is spend hours messing with your local settings only to find out in the end that it's the hardware at fault.

Bob Pullen
Plusnet Product Team
If I've been helpful then please give thanks ⤵

paulby
Grafter
Posts: 1,619
Registered: 26-07-2007

Re: DNS problems

@waldron
Did you change the DNS settings on the PC or on the router?
If your PC is set to obtain an IP address and DNS automatically from the router then most routers will hand out their own IP address as the DNS server.  The router will act as a proxy and will cache DNS lookups.  Rebooting the router solves problems with the DNS proxy in the router.
To rule out the router you should try manually setting the DNS servers on the PC (unless you've already tried that) and see how you get on.
To do this (assuming Xp) you need to go to Control Panel>Network Connections and right click on your ethernet (usually marked Local Area Connection) or wireless connection(depending on which your're using) and select properties.
Highlight Internet Protocol[TCP/IP] in the box that follows and select "properties" again.  On the page that follows select "Use the following DNS Server Addresses" and manually enter either PN's DNS servers or OpenDNS's.
If you've already tried this then, as Bob suggests, see if you can borrow a router first and rule out the hardware.
Wheel_nut
Grafter
Posts: 886
Registered: 03-08-2007

Re: DNS problems

I am seing this problem too. Pages are very slow to load and some BBC.co.uk pages failing to load particularly http://news.bbc.co.uk/sport1/hi/motorsport/formula_one/standings/default.stm
Is this the DNS problem again?
Edit: Disconnected and reconnected the PPPOA session (13 days old) and all seems well now.
Community Veteran
Posts: 19,100
Thanks: 437
Fixes: 21
Registered: 31-08-2007

Re: DNS problems

Did your gateway change as a result? If so, it could be gateway related.
waldron
Grafter
Posts: 348
Registered: 28-07-2007

Re: DNS problems

@Bob Pullen
I’ve made a note of the Google IP address and will try that next time it happens.
I’m running Zone Alarm on all my PCs/laptops.
Unfortunately I don’t have a spare router, nor do I know anyone who could lend me one (I have to use wireless throughout because of the location of my BT socket) so that is not an easy option.
@Paul03
I have the DNS servers set on the router (currently OpenDNS) and the Selection set to “Use User Discovered DNS Server Only”.
If I set the DNS server manually on this PC, would I need to similarly change all the other PCs/laptops and Disable DNS Relay on the router, or could the other PCs/laptops continue to use the automatic DNS (ie. Can I use a mixture or does it have to be ‘all or nothing’?) The laptops are both used in other locations.
I am running Vista, but have found the relevant properties window. Do I change TCP/IPv4 or TCP/IPv6 – or both?
@Anotherone
How do I find out which gateway I am using?
Thank you all for your help.
Wheel_nut
Grafter
Posts: 886
Registered: 03-08-2007

Re: DNS problems

Quote from: Anotherone
Did your gateway change as a result? If so,.......

Don't know.... I didn't check. The event log doesn't give me a clue. See below:
Recorded Events

Time Message

Info Jun 2 16:56:21 SNTP Synchronised to server: 91.186.12.87

Info Jun 2 16:26:23 FIREWALL event (1 of 1): disabled rules

Warning Jun 2 16:26:22 PPP link up (Internet) [212.159.45.56]

Info Jun 2 16:26:22 PPP CHAP Chap receive success : authentication ok

Info Jun 2 16:26:22 PPP CHAP Receive challenge (rhost = THN-AG1)

Info Jun 2 16:26:14 PPP CHAP Receive challenge (rhost = ERX19.Edinburgh4)

Info Jun 2 16:26:06 FIREWALL event (1 of 1): enabled rules

Warning Jun 2 16:26:04 PPP link down (Internet) [212.159.45.56]

Info Jun 2 15:56:21 SNTP Synchronised to server: 195.177.253.180

Info Jun 2 15:43:51 UPnP action 'AddPortMapping' from ip=192.168.1.68 (Action failed)

Info Jun 2 14:56:21 SNTP Synchronised to server: 217.112.84.107

Info Jun 2 13:56:21 SNTP Synchronised to server: 80.87.128.243

Info Jun 2 13:22:16 UPnP action 'AddPortMapping' from ip=192.168.1.68 (Success)

Info Jun 2 13:21:32 UPnP action 'AddPortMapping' from ip=192.168.1.68 (Success)

Info Jun 2 13:20:56 UPnP action 'AddPortMapping' from ip=192.168.1.68 (Success)

Info Jun 2 13:20:18 UPnP action 'AddPortMapping' from ip=192.168.1.68 (Success)

Info Jun 2 13:19:34 UPnP action 'AddPortMapping' from ip=192.168.1.68 (Success)

Info Jun 2 13:18:49 UPnP action 'AddPortMapping' from ip=192.168.1.68 (Success)

Info Jun 2 13:18:17 UPnP action 'AddPortMapping' from ip=192.168.1.68 (Success)

Info Jun 2 13:17:34 UPnP action 'AddPortMapping' from ip=192.168.1.68 (Success)

Info Jun 2 13:16:53 UPnP action 'AddPortMapping' from ip=192.168.1.68 (Success)

Info Jun 2 13:16:15 UPnP action 'AddPortMapping' from ip=192.168.1.68 (Success)

Info Jun 2 13:15:44 UPnP action 'AddPortMapping' from ip=192.168.1.68 (Success)

Info Jun 2 13:15:06 UPnP action 'AddPortMapping' from ip=192.168.1.68 (Success)

Info Jun 2 13:14:30 UPnP action 'AddPortMapping' from ip=192.168.1.68 (Success)

Info Jun 2 13:13:52 UPnP action 'AddPortMapping' from ip=192.168.1.68 (Success)

Info Jun 2 13:13:19 UPnP action 'AddPortMapping' from ip=192.168.1.68 (Success)

Info Jun 2 13:12:35 UPnP action 'AddPortMapping' from ip=192.168.1.68 (Success)

Info Jun 2 13:12:00 UPnP action 'AddPortMapping' from ip=192.168.1.68 (Success)

Info Jun 2 13:11:23 UPnP action 'AddPortMapping' from ip=192.168.1.68 (Success)

Info Jun 2 13:10:42 UPnP action 'AddPortMapping' from ip=192.168.1.68 (Success)

Info Jun 2 13:10:03 UPnP action 'AddPortMapping' from ip=192.168.1.68 (Success)

Info Jun 2 13:09:25 UPnP action 'AddPortMapping' from ip=192.168.1.68 (Success)

Info Jun 2 13:08:46 UPnP action 'AddPortMapping' from ip=192.168.1.68 (Success)

Info Jun 2 13:08:06 UPnP action 'AddPortMapping' from ip=192.168.1.68 (Success)

Info Jun 2 13:07:26 UPnP action 'AddPortMapping' from ip=192.168.1.68 (Success)
Community Veteran
Posts: 3,291
Thanks: 2
Registered: 10-08-2007

Re: DNS problems

@Waldron, you can check which gateway you are on  here Usertools Gateway Checker
waldron
Grafter
Posts: 348
Registered: 28-07-2007

Re: DNS problems

@Santiago. Thanks - I'll try to check each time I start the router while this problem is ongoing.
paulby
Grafter
Posts: 1,619
Registered: 26-07-2007

Re: DNS problems

Quote
I have the DNS servers set on the router (currently OpenDNS) and the Selection set to “Use User Discovered DNS Server Only”.
If I set the DNS server manually on this PC, would I need to similarly change all the other PCs/laptops and Disable DNS Relay on the router, or could the other PCs/laptops continue to use the automatic DNS (ie. Can I use a mixture or does it have to be ‘all or nothing’?) The laptops are both used in other locations.
I am running Vista, but have found the relevant properties window. Do I change TCP/IPv4 or TCP/IPv6 – or both?

You can set the DNS servers manually on any PC without having to change settings on the others or the router.
As you're running Vista you should *disable* TCP/IPv6 by unticking the box next to it - actually try doing this first before setting the DNS manually in IPv4 as having IPv6 enabled (which you don't need) has been known to cause problems.  If disabling IPv6 works then all is well.  If not, enter the DNS manually in IPv4.
waldron
Grafter
Posts: 348
Registered: 28-07-2007

Re: DNS problems

@Paul03. Thanks. I've disabled TCP/IPv6 - I'll see how that goes before changing the DNS.
waldron
Grafter
Posts: 348
Registered: 28-07-2007

Re: DNS problems

I had no problems for the remainder of last week, but it happened again at 3 pm today. I already had one IE8 session (to Ubuntu forums) working successfully, but I couldn't access any other websites. Tried navigating directly to Google (216.239.59.104)  which was successful.
I then booted up my laptop (Vista) and had exactly the same problem there. The diagnostics said "Windows cannot find the hostname "www.google.co.uk" using DNS, although I could get to Google using the IP address.
I rebooted my main PC, but this time the network came up as 'Local only'. I then changed network connections to access DNS directly, and not via the router. That worked successfully straight away.
Does this imply a router problem (as Bob Pullen suggested earlier) possibly with the DNS allocation?
In the DNS section of the router, there are two options - "Use Auto Discovered DNS Server Only" and "Use User Discovered DNS Server Only". Which one should I be using?