DNS issues

[#1]

Thought I'd post here as it may help others.  For a few weeks now I have problems with plusnet's DNS servers (browsers showing 'resolving host' for lengthy amounts of time and also timing out / erroring).

I originally thought there was no way to change DNS server as it's locked into the router settings, but you can override the settings in your operating system. (Windows or Mac etc.) which I didn't realize.

Changing to Googles public DNS servers fixed my problems so worth a try if you're having connection / dns problems.

https://developers.google.com/speed/public-dns/docs/using

[#2]

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@FaTony wrote:

Changing to Googles public DNS servers fixed my problems so worth a try if you're having connection / dns problems.

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@FaTony Welcome to the forum. 🙂

Google's DNS is undoubtedly good, but benchmark testing reveals BT's 62.6.40.178 and 194.74.65.69 to be even better at my location. YMMV.

Other BT servers here .

[#3]

@FaTony we're not aware of any issues affecting our DNS caches. I'd be interested to know if your problem goes away by specifying Plusnet's DNS at the operating system layer. You can use any of the following:-

212.159.6.9
212.159.6.10
212.159.13.49
212.159.13.50

If the problem goes away after trying those, then the issue looks unlikely to be caused by our DNS servers, and instead could be an issue with your router that sits in between the DNS proxying requests. By default, the DNS address your devices use will be that of the router - i.e. 192.168.1.254 - requests are sent to the router, and the router then forwards them upstream to our servers. 

[#4]

Hmmm using 212.159.6.9 within windows configuration does seem to work

Removing all OS overrides then brings the problem back?

Why would the router have problem resolving domain names?  I'm using the basic plusnet hub one where you can't change the DNS settings ... what other settings could be causing the problem?

[#5]

Interesting, thanks @FaTony 

It sounds like it could be due to an acknowledged problem (see here).

If you open a Windows command line and carry out the following two lookups, what happens?

nslookup bbc.co.uk 192.168.1.254

nslookup bbc.co.uk 212.159.6.10

 Do either of them fail? And if so, what error is returned?

[#6]

nslookup bbc.co.uk 192.168.1.254
Server: dsldevice.lan
Address: 192.168.1.254

Non-authoritative answer:
Name: bbc.co.uk
Addresses: 2a04:4e42::81
2a04:4e42:400::81
2a04:4e42:200::81
2a04:4e42:600::81
151.101.128.81
151.101.0.81
151.101.192.81
151.101.64.81

nslookup bbc.co.uk 212.159.6.10
Server: cdns02.plus.net
Address: 212.159.6.10

Non-authoritative answer:
Name: bbc.co.uk
Addresses: 2a04:4e42::81
2a04:4e42:400::81
2a04:4e42:200::81
2a04:4e42:600::81
151.101.192.81
151.101.64.81
151.101.0.81
151.101.128.81

[#7]

Thanks, both of those look OK which suggests your router is returning a DNS response. Are things in the error state now?

I'm using a Hub One at the moment and according to my monitoring, a DNS query to the router rather than direct adds ~14ms to the round trip time. That's barely perceivable though, and I wouldn't expect it to have led to you feeling you needed to fiddle with things.

I've seen examples in the past where lookups to the router fail 100% of the time until the device is rebooted but this doesn't look like one of those instances

[#8]

Yea seems like an intermittent issue, as it would stay stuck 'resolving host' (in chrome status bar) at random times, then refreshing sometimes would load instantly, sometimes you would get to a chrome error page etc.

Doesn't seem to be happening now I've set the DNS settings in Windows, however I think the issue is affecting other devices on my network ..

[#9]

Very difficult to establish what's going on without being able to put the device in a persistent error state. When the problem is occurring a Wireshark packet capture from an affected machine might provide some clues, but I'd only suggest it if you're technically inclined?

[#10]

yea dont' worry - it's very intermittent so would be very difficult to run a test when it fails, sometimes wait 4-5 seconds for page to load 'resolving host' then hit F5 and it loads instantly the next time.

[#11]

Hi I have a similar issue to this. Intermittent problems with DNS lookup. I am using a standard plusnet hub. Only a reboot fixes and then it is OK for a few hours

I have already identified that bypassing the default router in a device works OK, but I have 30+ various devices and I do not want to have make manual changes to all of them. It has worked for years so I am trying to understand what is wrong.

I have tried the tests above and these are the results

C:\Users\kevin>nslookup bbc.co.uk 192.168.1.254
Server:  dsldevice.lan
Address:  192.168.1.254

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

C:\Users\kevin>nslookup bbc.co.uk 212.159.6.10
Server:  cdns02.plus.net
Address:  212.159.6.10

Non-authoritative answer:
Name:    bbc.co.uk
Addresses:  2a04:4e42::81
          2a04:4e42:200::81
          2a04:4e42:400::81
          2a04:4e42:600::81
          151.101.0.81
          151.101.64.81
          151.101.128.81
          151.101.192.81
C:\Users\kevin>

So I am wondering if anyone has got to the bottom of this issue.

I am thinking there may have been a remote update to the router firmware that has broken the DNS service on the router?