The reports of web pages taking far too long to load, or where only some images on a web page are loading - e.g. not all the thumbnails showing up on an ebay listing, suggests something else altogether.
Possibly it's a problem with web proxy caching. BT used to rely on Squid for web proxy caching. Maybe it still does; if so it was/is known to be riddled with insecurities; many ways to cripple it with DDOS.
Im not sure.
Re Web caching - I didnt think BT used it on their network. afaik AOL was the only UK ISP that used to do any sort of web caching. AOL users tended to run into difficulty on a couple of pages on my main site such as the 'rate my ISP' page because of web caching.
PN dabbled with squid many years ago for a very short period and very prompty ditched it as one massive failure.
Unlike 10 yrs ago, theres far too many dynamically generated pages for it to be of much use at an ISP level. AFAIK web caching these days is just mostly used for business/organisations/education who may be on a slowish connection and need to conserve downstream bandwidth.
Web caching doesnt save the ISP that much bandwidth where it matters most - its core bandwidth that is the most expensive so web caching is a waste of time. Transit bandwidth is comparitively cheap. They do DNS caching though.
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Re the problem with ebay, that could still be a DNS issue.
The structure of the ebay site means that there are going to be lots of DNS calls per page.
When you visit most websites images will be stored on the same domain. ie for this site images will likely be in a folder
kitz.co.uk/images or say
kitz.co.uk/adsl/images. Because you are already on the site calling for an image in a sub folder on the domain doesnt require DNS lookups.
AIUI DNS is needed though each time you call a new domain or subdomain. so that for example would be anything designated with a . (dot) rather than than the afterwards /
eg the subdomains for the forum when on the main site would require a new DNS call because they could be hosted on a different server.
forum.kitz.co.uk/index.php
wiki.kitz.co.uk/index.php
So going back to ebay, all the images are scattered all over the place and held on many different servers and locations.
Youve already looked up ebay.co.uk and the page is trying to load, but then note where all the images are coming from, theyre not held on the same domain.. but broken down into lots of subdomains on a separate domain.
http://thumbs.ebaystatic.com/d/
http://thumbs1.ebaystatic.com/d/
http://thumbs4.ebaystatic.com/d/
http://thumbs3.ebaystatic.com/d
http://s1.thcdn.com/
Surely such a page is going to be
very intensive for DNS?