DNS servers failing

[#1]

Quote from: Townman

Quote from: Oldjim Not correct otherwise all the BQM graphs would have shown it That would depend on what the problem was.  I saw the problem but had no issue connecting to thinkbroadband.com - it is that experience that leads me to believe this was a routing issue and not a DNS issue. different between PlusNet's DNS and Google's DNS - they appear to be in separate sub-nets with no overlap.  Therefore I suggest it is possible that PlusNet could route to one subnet and not the other. This is all speculation

Speculation or not that sounds like a plausible explanation and would make a lot of sense why some sites were reachable but not others.

[#2]

Which sites were you able to reach vs unable to reach?

[#3]

Hi Andy,
In my case, the limited set of testing that I did - it was late and SWMBO was ready for bed - I went through the multiple pages I had 'open' on the iPad.
From memory I could access...
this forum
lcn.com
plus.google.com
thinkbroadband.com (went there looking for posts about the problem)
mrexcel.com
mapmaker.com
I could not access
www.gov.uk
google.co.uk
bbc.co.uk
moneysavingexpert.com
Without having done detailed analysis at the time, it is not possible to be sure what was going on.  One might suggest that those that worked had their DNS resolutions cached, whilst those that did not needed a DNS lookup.  That needs consideration of TTL values and when they were last retrieved.  I'm using default DNS settings, so my router is acting as cache / proxy (?) and had not had a PPP reset for 65 days.  Gateway is ptn-ag01.  Those that succeeded I use less frequently (aside for this forum) than those that failed which kind of knocks the possibility of cached DNS resolution on the head ... and leads me to have considered routing as the cause of the issue.
Hope that might help in some way.
Kevin

[#4]

In a post on Usenet, Bob Pullen has confirmed:
[quote=news://usenet.plus.net:119/57adnXKwLtqBBW_InZ2dnUU78eudnZ2d@brightview.co.uk]In short, a routing problem. The DNS observations were a by-product.

[#5]

Pitchforks at the ready lads!

dick:quote

[#6]

Wow! A 14 page thread with 214 post constantly updated in a very short space of time silenced with a single line. That single line of course being an explanation to the cause, now there has to be a lesson in there somewhere.

[#7]

PlusNet was likely just following government orders and cocked up its DNS?  If people really want to view porn, they will find a way like using the dark web.
I use OpenDNS.  This issue made me aware of the possibility that PlusNet DNS is checking my resolution requests (for porn sites?) before passing them to OpenDNS.  That could explain slower web browsing of late.

[#8]

IMO that's extremely unlikely, but if you're concerned about DNS security have a look at this:
https://www.opendns.com/about/innovations/dnscrypt/