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Plusnet DNS server not respecting source TTL

pv
Dabbler
Posts: 22
Registered: ‎12-06-2019

Plusnet DNS server not respecting source TTL

I have noticed that Plusnet's DNS servers set a hard cap of 900 seconds (15 minutes) on the TTL (Time To Live) of the DNS records it supplies.

 

For instance, plusnettest.mooo.com has a TTL of 3600 seconds (1 hour) but when I query the Plusnet DNS servers it comes back with a TTL of 900 seconds (15 minutes). I have pasted the responses from Plusnet's DNS server and Google's DNS server for comparison.

 

Please can someone at Plusnet make sure the correct TTL is supplied by the Plusnet DNS server, so as to reduce the number of DNS lookups clients need to make?

 

 

Plusnet DNS (TTL 900 seconds):

 

C:\>dig @213.120.234.42 plusnettest.mooo.com

; <<>> DiG 9.14.4 <<>> @213.120.234.42 plusnettest.mooo.com
; (1 server found)
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 44618
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;plusnettest.mooo.com.          IN      A

;; ANSWER SECTION:
plusnettest.mooo.com.   900     IN      A       80.1.1.1

;; Query time: 123 msec
;; SERVER: 213.120.234.42#53(213.120.234.42)
;; WHEN: Fri Aug 09 12:31:46 GMT Summer Time 2019
;; MSG SIZE  rcvd: 65

 

 

Google DNS (TTL 3600 seconds):

 

C:\>dig @8.8.8.8 plusnettest.mooo.com

; <<>> DiG 9.14.4 <<>> @8.8.8.8 plusnettest.mooo.com
; (1 server found)
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 57273
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 512
;; QUESTION SECTION:
;plusnettest.mooo.com.          IN      A

;; ANSWER SECTION:
plusnettest.mooo.com.   3599    IN      A       80.1.1.1

;; Query time: 113 msec
;; SERVER: 8.8.8.8#53(8.8.8.8)
;; WHEN: Fri Aug 09 12:30:02 GMT Summer Time 2019
;; MSG SIZE  rcvd: 65

 

36 REPLIES 36
Superuser
Superuser
Posts: 3,192
Thanks: 898
Fixes: 7
Registered: ‎06-04-2007

Re: Plusnet DNS server not respecting source TTL

It looks like it is just the SafeGuard DNS servers that are changing it.  The normal ones are returning the original values.

pv
Dabbler
Posts: 22
Registered: ‎12-06-2019

Re: Plusnet DNS server not respecting source TTL

I have SafeGuard switched off.

Plusnet Help Team
Plusnet Help Team
Posts: 13,385
Thanks: 4,126
Fixes: 665
Registered: ‎21-04-2017

Re: Plusnet DNS server not respecting source TTL

Hi there.

Is this causing any connection problems in particular with your service?

If this post resolved your issue please click the 'This fixed my problem' button
 Anoush Mortazavi
 Plusnet Help Team
pv
Dabbler
Posts: 22
Registered: ‎12-06-2019

Re: Plusnet DNS server not respecting source TTL

It results in more DNS queries being sent than is required, which has a performance impact.

 

My question still stands, why is the Plusnet DNS server not respecting the source record TTL?

Plusnet Help Team
Plusnet Help Team
Posts: 13,385
Thanks: 4,126
Fixes: 665
Registered: ‎21-04-2017

Re: Plusnet DNS server not respecting source TTL

As far as I'm aware this isn't something we have visibility of from a customer support point of view. I've tested your line and there don't seem to be any issues with the broadband signal coming into your router.

Could you provide more information on the performance issues you are experiencing please?

If this post resolved your issue please click the 'This fixed my problem' button
 Anoush Mortazavi
 Plusnet Help Team
pv
Dabbler
Posts: 22
Registered: ‎12-06-2019

Re: Plusnet DNS server not respecting source TTL

Can you please show this thread to someone who is responsible for managing the Plusnet DNS servers and ask them what they think about the issue I have raised?

Plusnet Help Team
Plusnet Help Team
Posts: 13,385
Thanks: 4,126
Fixes: 665
Registered: ‎21-04-2017

Re: Plusnet DNS server not respecting source TTL

Thanks for getting back to us.

I've discussed this with my colleagues on the social media/community team and I feel I'd struggle to find the right person to look into this without knowing exactly what performance problems you're experiencing I'm afraid.

If this post resolved your issue please click the 'This fixed my problem' button
 Anoush Mortazavi
 Plusnet Help Team
pv
Dabbler
Posts: 22
Registered: ‎12-06-2019

Re: Plusnet DNS server not respecting source TTL

I think I've made it quite clear this relates to the misconfiguration of your DNS servers. Are you really unable to determine the best person to speak to at Plunset about this?

Plusnet Help Team
Plusnet Help Team
Posts: 13,385
Thanks: 4,126
Fixes: 665
Registered: ‎21-04-2017

Re: Plusnet DNS server not respecting source TTL

While I understand you've said you believe our DNS servers are misconfigured, do you mind me asking what issues this is causing you so I can get this investigated the appropriate way.

If this post resolved your issue please click the 'This fixed my problem' button
 Anoush Mortazavi
 Plusnet Help Team
pv
Dabbler
Posts: 22
Registered: ‎12-06-2019

Re: Plusnet DNS server not respecting source TTL

I've outlined the issue comprehensively in my opening post. I've explained that this causes extra DNS queries which has a performance impact for everyone who uses your DNS servers, due to the extra queries.

 

If you are unable to assist further please escalate it as a complaint.

Plusnet Help Team
Plusnet Help Team
Posts: 13,385
Thanks: 4,126
Fixes: 665
Registered: ‎21-04-2017

Re: Plusnet DNS server not respecting source TTL

Thanks for getting back to us.

While I understand you'd like to raise this as a complaint, in order to investigate what you've said as a complaint or otherwise we need to know more information I'm afraid. As part of our Customer Advocates department both myself and my colleagues on the social media team who respond via the community forums are in the best position to deal with your complaint.

With that in mind, as our testing hasn't identified any issues with your service to investigate further please connect your computer/laptop to the router with an ethernet cable and run the BT Speedtester service at http://speedtest.btwholesale.com You must ensure that you have no other programs running at the same time such as streaming, general browsing and the most common one is antivirus programs downloading updates in the background.

Once the initial result is completed please click Further Diagnostics then type your phone number in and click run diagnostic test. This will run a test and send the results to the BT server for investigation. Once you have completed this, please report a fault to us at http://faults.plus.net letting us know over here once you've completed it and we'll make sure it is picked up as soon as possible. 

Thanks again.

If this post resolved your issue please click the 'This fixed my problem' button
 Anoush Mortazavi
 Plusnet Help Team
pv
Dabbler
Posts: 22
Registered: ‎12-06-2019

Re: Plusnet DNS server not respecting source TTL

You aren't best placed to answer my query as you don't seem to understand DNS TTL and the performance impact of making unnecessary DNS queries. The fact you are asking me to run a speed test is stark proof of this.

 

I requested this to be escalated as a complaint so that I may speak to someone who does understand these things, and you don't even seem willing to do that.

 

Not good enough.

Plusnet Help Team
Plusnet Help Team
Posts: 13,385
Thanks: 4,126
Fixes: 665
Registered: ‎21-04-2017

Re: Plusnet DNS server not respecting source TTL

Thanks for getting back to us.

The test I'm asking you to run tests your throughput and allows us to progress a fault investigation. 

I'm trying to find the right person to discuss this with, please bear with me.

If this post resolved your issue please click the 'This fixed my problem' button
 Anoush Mortazavi
 Plusnet Help Team
Plusnet Help Team
Plusnet Help Team
Posts: 13,385
Thanks: 4,126
Fixes: 665
Registered: ‎21-04-2017

Re: Plusnet DNS server not respecting source TTL

I've discussed this with a colleague from our networks team and I'm advised that the DNS server you've quoted above aren't Plusnet. Our DNS servers can be found Here.

To set standard DNS server addresses
Primary 212.159.13.49
Secondary 212.159.13.50
To set alternative DNS server addresses
Primary 212.159.6.9
Secondary 212.159.6.10

If you're referring to Safeguard DNS 

To set Plusnet Safeguard DNS server addresses
Primary 213.120.234.42
Secondary 213.120.234.42

I'm advised that's to ensure that things aren't cached for too long and this shouldn't be affecting your service in any way.

Hope this helps.

If this post resolved your issue please click the 'This fixed my problem' button
 Anoush Mortazavi
 Plusnet Help Team