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Contributor
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Message 1 of 5

DNS timeouts

These last few days my HH5 has started to play up with regards DNS lookups. My PC's are configured using DHCP so the DNS server is the HH5 (192.168.1.254) and if I attempt to use nslookup when the problem occurs the I get responses as follows:

 

nslookup www.bbc.com


DNS request timed out.
timeout was 2 seconds.
Server: UnKnown
Address: 192.168.1.254

DNS request timed out.
timeout was 2 seconds.
DNS request timed out.
timeout was 2 seconds.
DNS request timed out.
timeout was 2 seconds.
DNS request timed out.
timeout was 2 seconds.
*** Request to UnKnown timed-out

 

when it works I get 

 

nslookup www.bbc.com
Server: BThomehub.home
Address: 192.168.1.254

Non-authoritative answer:
Name: www-bbc-com.bbc.net.uk
Addresses: 212.58.244.69
212.58.244.68
Aliases: www.bbc.com

 

 

if I attempt to use google dns during the "broken" preiod then the hub works fine and routes accordingly.

 

the DNS configuration on my HH5 says this (during a working period)

 

 

TCP/IP settings
Broadband network IP address:86.183.88.225 
Default gateway:172.16.14.137 
Primary DNS:31.55.185.70 
Secondary DNS:31.55.187.38 
 

 

I am very close to the exchange and normally get over 70Mbs connection so it unlikely to be flakey.

 

Any ideas why this might be happening ?

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4 REPLIES 4
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Contributor
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Message 2 of 5

Re: DNS timeouts

It could be that BT have done something wonky again - but havent seen lots of posts about this which normally happens when someone stuffs up DNS.

 

So firstly I would factory reset your router.

 

Without getting you to post more elaborate IPCONFIG tables and or knowing everything connecting to your network can I suggest it looks like your router is a tad confused. Other culprits could be tethered mobiles connecting to two networks or malware.

 

All I can tell from your post is that one DNS request failed - and one succeeded. If as you say it appears to work using Google DNS then I suggest you use that in future. Personally I prefer to use Google as Primary and Open DNS as Secondary

 

In this bit :

 

TCP/IP settings
Broadband network IP address:86.183.88.xxx 
Default gateway:172.16.14.xxx 
Primary DNS:31.55.185.70 
Secondary DNS:31.55.187.38 

 

We have your IP - dynamicly allocated by BT

The Default Gateway - while your router is your gatway to the modem component of the HH5 this is the Modems Gateway to BT - and the Primary and Sec DNS servers belong to BT

 

BTs DNS servers have come in for some critisism in the past : and remember that the failure of a DNS lookup can also be caused by an exceptional 'delay' in that request being passed on (slow speed) causing a 'time out event'.

 

 

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Aspiring Expert
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Message 3 of 5

Re: DNS timeouts

Its funny you mentioned about the default gateway mine is this on my HH5A -

Default gateway: 172.16.18.135

I apologise for randomly butting in this thread. I have had a few DNS related issues. With slow pages and needing to refresh things from time to time.
My DNS via the HH5 reads -
Primary DNS: 31.55.186.70
Secondary DNS: 31.55.185.18
I only noticed this issue not long ago. So maybe it's an issue creeping around slowly. Hopefully not though. 😞
*This is my signature...it's a bit boring*
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Contributor
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Message 4 of 5

Re: DNS timeouts

If you were reading that as I was editing it I realised the BT21 network was using internal corporate addresses as gateways. 🙂

So quickly redacted most of what I had typed about the 172 range << tho I was right in that it isn't normally used in a home SMB network environment.

 

Unfortunately that left my initial diagnosis well off the mark hence the quick edits.

 

Re the BT21CN Gateways tho - it wouldnt surprise me if there were 'pinch points' along the way on these and it would be interesting to map these ranges against locations << I bet OpenReach have an App for that, or it may be that they are themselves dynamicly allocated at which point you have to wonder where the plug is.

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Aspiring Expert
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Message 5 of 5

Re: DNS timeouts

Thank you for clarifying - I was unsure about the nature of it lol.
Insomnia really makes you think the worst at this time in the morning.
I won't hijack this thread anymore. I do hope this DNS thing isn't going to be big like it was in December ugh 🙂
*This is my signature...it's a bit boring*
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