DNS Stops working every hour or so (Not the server)

[chris6273]

Hi guys,

For some reason recently my home network has been playing up. Every hour or so the DNS will conk out and stop working for around 3-5 minutes until it kicks back into life again. Data still transfers to the internet while this DNS issue is occuring.

I have tried using Open DNS Servers and my standard BT DNS Servers.

I can confirm it doesn't work because Chrome says "Sending Request" and when trying to ping bbc.co.uk it doesn't resolve.

Does anyone know where the issue may lie? Router or ISP?

My Server has issues at exactly the same time and uses different DNS servers. I've tried Open DNS Servers as well as my standard ISP Servers.

Any ideas? It's really annoying!

Thanks for your Help.

 

[chris6273]

So if you ping the IP it works?

Yes, it keeps working throughout the problem.

if u have 2 computers both with manual and different DNS, its ur webs. BT ur ISP ye? so u tried open DNS, BT's DNS, used googles? i wouldn't expect to make a difference (8.8.8.8) have you also tried (unsure if option available on BT's router) to ping a website from the ROUTER, at least if that fails you can point towards that, and drop your PC's out of the issue

but any existing connections to the internet remain during this process...but you cant browse yeah? i'd be running 2 constant ping tests, 1 on local network and 1 to a website, leave them, see if they drop during this, but have them running before the issue presents its self.

BT is my DNS, yes. Yes I have and it fails from the router as-well.

None of the pings drop throughout the problem. This is mainly because DNS isn't required to ping an IP after the domain for it has initially been resolved.

what router do you have?

I have a Billion 7800N.

Any Ideas?

 

[chris6273]

Nope all DoS settings are disabled. Also nothing has changed since it used to work.

 

[chris6273]

Sorry for the late reply guys, seems the email notification system on the forums is broken.

What I have done so far is put a HomeHub on the line and as soon as I put it on, the problems stopped. So it seems to be a fault with the 7800N I have.

It's nothing to do with Google Chrome because I can't resolve IPs on the router or my server.

I've tried to set up OpenDNS Servers on the router but it didn't make a difference. Seems to be the router not routing DNS requests.

Something weird is when the problem is occurring and I try to 'set vc' in nslookup, the DNS Requests can get through (Setting VC sets DNS Requests for nslookup to use TCP/IP instead of UDP).

When setting it back to 'set novc' (Back to UDP) queries don't get through until the router decides to kick back to life.

It isn't a problem with my line because the HomeHub works on it flawlessly (And is such an inferior router than the 7800N), so it seems UDP packets are not getting through for DNS.

Could it be a hardware fault? Because I've tried two different Firmware versions and both haven't worked when they used too?

Thanks for your help

 

[chris6273]

Setup the DNS on the computer itself so it bypasses the DNS servers stored on the router.

I've tried that but it didn't make any difference. Seems I forgot to add a list of things I've tried in my first post:

• Changing DNS Servers both on my Computer & on my Routers' DHCP Server to OpenDNS Servers.
• Doing a complete factory reset of my 7800n
• Resolving a domain on my modem interface when the DNS problem occurs (Times out)
• Resolving a domain name on my Server - Same problem
• Leaving it a few days and trying again; this problem has been happening for over a week now

Did you restore the router to factory settings after changing the firmware? Billion are pretty adamant that you should do this.

Yes; I did it when specifying the firmware file on each reflash and I've tried it after flashing as-well on one occasion.

Any more ideas?

 

[chris6273]

Wireshark just shows the packet being sent to 10.5.14.254 (The router) and not receiving any response when the issue is occurring. When it starts working again it gets responses back.

Yes I am in contact with Billion but haven't got very far so far. They have sent me a configuration file which appears to have set the DNS servers to Googles' 8.8.8.8 but hasn't made one bit of difference.

I've noticed that YouTube stops buffering when the DNS issue occurs; could this reinforce the theory that my 7800N stops routing UDP packets when the issue occurs? If so it would rule out an isolated DNS issue and would explain why only UDP DNS Requests are being rejected while TCP/IP requests are working.

Are there any UDP tests I can complete DNS-free while the connection is being problematic over the internet? I have seen software for doing it but I'd require a server on the internet side of the router to test properly.