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Plusnet gateway and DNS problems

Townman
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Re: Plusnet gateway and DNS problems

That is somewhat different from the historical experience of this issue.  I have found the long history here - https://community.plus.net/t5/ADSL-Broadband/198-18-1-x-address-problems/m-p/1171271#M279937 - that post reference some diagnostic queries to fire at the router, particularly...

dns server debug spoof list

 

Edit - crossing posts - @MisterW  - which means we are not looking at the historical issue, but something different! 

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MisterW
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Re: Plusnet gateway and DNS problems

https://community.plus.net/t5/ADSL-Broadband/DNS-Issues-Technicolor-TG582n/td-p/1087188

Probably a hiccup in the version of dnsmasq used by the tg582n

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avant-guvnor
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Re: Plusnet gateway and DNS problems

How would you explain the issue occurring with a static ip and not a dynamic ip and, only starting 2 months ago? 

Townman
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Re: Plusnet gateway and DNS problems

Do the static and dynamic IP addresses refer to the same DNS servers?

Thinking about @MisterW 's comment about you using Google DNS, I thought it is not possible to change the DNS servers in this router?

Post #7 in the last link is a useful diagnostic from @npr the recognised (customer) guru on these routers!

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MisterW
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Re: Plusnet gateway and DNS problems

thought it is not possible to change the DNS servers in this router?

Using the cli it is

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MisterW
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Re: Plusnet gateway and DNS problems

How would you explain the issue occurring with a static ip and not a dynamic ip and, only starting 2 months ago? 

The difference between dynamic and static ip could well be down to different routing across the network. I suspect that dnsmasq is intermittently getting timeouts from the real dns servers and then giving up for a short period. As to why it started recently, I have no answer 

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avant-guvnor
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Re: Plusnet gateway and DNS problems

Summary:
Issue started 2 months ago. Static ip with Google dns servers (IIRC I also tried the Cloudflare dns servers) so, I configured router to use Plusnet dns servers and issue continued.

Over a week ago, @Gandalf  configures my account to use a dynamic ip and no issue for 7+ days.

Yesterday, @Gandalf  reverts account back to static ip and in less than 24 hours, issue returns.

avant-guvnor
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Re: Plusnet gateway and DNS problems

@MisterW  I suspect that dnsmasq is intermittently getting timeouts from the real dns servers and then giving up for a short period.

Is this timeout setting something I can configure in the router?

MisterW
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Re: Plusnet gateway and DNS problems

Not as far as I am aware. The TG582 is a bit long in the tooth now. Gandalf has sent you a new router I believe. Lets see how it goes with that.

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pvmb
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Re: Plusnet gateway and DNS problems


@Townman wrote:
If this is the historical TG582n and Win 8/8.1/10 IP address spoofing issue then I doubt a static / public IP address will make any difference.

With this problem I have seen two browser windows pointing at the same website work and not work concurrently.

Flushing the device’s DNS cache is a good test to see if this is the problem “in play”.

Yes! I am familiar with this. If it is, then it could be time for the old Command Prompt: IPCONFIG /flushdns command. Then wait a bit.

Though why only now? Changes to PC OS? Anything else?

Townman
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Re: Plusnet gateway and DNS problems


@avant-guvnor wrote:

Over a week ago, @Gandalf  configures my account to use a dynamic ip and no issue for 7+ days.

Yesterday, @Gandalf  reverts account back to static ip and in less than 24 hours, issue returns.


Interesting!!

When I had all of the issues back in history (!) I was on a static IP address - the influence of that never hit the radar screen at that time.  The fact that it has done so here suggests a network performance consideration, for (I believe that) whilst the DNS server specification is the same regardless of the IP type in use, the network path to the same could well be different.

Here's mine from a 84.92.x.x static IP address...

#Microsoft Windows [Version 10.0.19041.985]
#06/06/21-21:24:16.49
C:\Users\Kevin>tracert 212.159.6.9

Tracing route to cdns01.plus.net [212.159.6.9]
over a maximum of 30 hops:

  1     4 ms     2 ms     1 ms  192.168.1.254
  2    10 ms    10 ms    10 ms  250.core.plus.net [195.166.130.250]
  3   198 ms    10 ms    22 ms  84.93.253.87
  4    10 ms    10 ms    10 ms  cdns01.plus.net [212.159.6.9]

Trace complete.

 

OK this is becoming scary!!  Just ran the same tracert on another user's service in the 80.229.x.x static IP pool...

C:\Users\Steve>tracert 212.159.6.9

Tracing route to FWDR-9.FWDR-6.FWDR-159.FWDR-212 [212.159.6.9]
over a maximum of 30 hops:

  1     1 ms     1 ms     1 ms  dsldevice.lan [192.168.1.254]
  2    12 ms    13 ms    13 ms  251.core.plus.net [195.166.130.251]
  3    13 ms    13 ms    13 ms  84.93.253.95
  4    14 ms    16 ms    14 ms  FWDR-9.FWDR-6.FWDR-159.FWDR-212 [212.159.6.9]

Trace complete.

 

Note the different rDNS identifier for the same IP address on line #4.

@Gandalf does this rather suggest that depending on which gateway a user comes into the network via, they are accessing a different (DNS) server for the same IP address?

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