what speed test to trust.

[#1]

I have been a customer with plusnet for coming up to six months now,  started on the unlimited service, and moved to the premium service.  Now I believe that I have been moved to the ADSL2+ service. 
I have run several test at different times of the day, on various different sites, each time and each different website i have recieved different results.  Now for what i use the web for I am not to bothered about the speed i recieve as at the end of the day i do what i need, but I would love to understand what the running speed of my service should be, and what the adsl2+ service does for my service?  just to understand why speed is so important on the net.  Also why do i get a different speed result on different sites? is it to do with the other isp paying those sites off?
i look forward to hearing from you in the near future

[#2]

any speed test site will start to give out a higher % of dud tests over the 8mb product when you start getting in to the 10-20mb throughput zone
speedtest.net varries from server to server in my opion, bt one can be a rite pig esp in the early days of 21cn. at my low sync rate of 3500kbps the mybroadbandspeed one is this most stable and cant remember geting a dud test  on there ever

[#3]

http://www.speedtest.bbmax.co.uk/ is my usual choice, always accurate for me at least

[#4]

Obviously http://www.speedtester.bt.com/ ; comes at the top of the list to find out your IP Profile. Also as this is given high priority on the Plusnet network for all account types it gives your maximum possible speed.
The usual controlling factor on your speeds is the link between your PC and the Plusnet gateways, the traffic congestion on your exchange, the congestion on the Plusnet gateways and the shaping applied to Plusnet to your traffic. It therefore makes sense to use a tester which is as close as possible to the Plusnet gateways, and none is closer than the speed tester run by Plusnet themselves which is http://www.mybroadbandspeed.co.uk/ This uses the same speed test engine (Ookla) as speedtest.net
If you want an independent speed tester I'd recommend http://www.thinkbroadband.com/speedtest.html which is again very close to the Plusnet suite in London as evidenced by the pings below which are almost the same as to the Plusnet tester (I'd hazard a guess it might even be in the same building).
Finally, if you use the BBC iPlayer, they have their own diagnostic speed tester which does tests emulating streaming: http://www.bbc.co.uk/iplayer/diagnostics

C:\Documents and Settings\John>ping www.mybroadbandspeed.co.uk
Pinging www.mybroadbandspeed.co.uk [84.92.1.14] with 32 bytes of data:
Reply from 84.92.1.14: bytes=32 time=11ms TTL=60
Reply from 84.92.1.14: bytes=32 time=11ms TTL=60
Reply from 84.92.1.14: bytes=32 time=9ms TTL=59
Reply from 84.92.1.14: bytes=32 time=10ms TTL=60
Ping statistics for 84.92.1.14:
    Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
    Minimum = 9ms, Maximum = 11ms, Average = 10ms
C:\Documents and Settings\John>ping www.thinkbroadband.com
Pinging www.thinkbroadband.com [80.249.99.130] with 32 bytes of data:
Reply from 80.249.99.130: bytes=32 time=10ms TTL=57
Reply from 80.249.99.130: bytes=32 time=13ms TTL=57
Reply from 80.249.99.130: bytes=32 time=11ms TTL=57
Reply from 80.249.99.130: bytes=32 time=13ms TTL=57
Ping statistics for 80.249.99.130:
    Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
    Minimum = 10ms, Maximum = 13ms, Average = 11ms

[#5]

For line testing , and speed issues with PlusNet. you will need to use the BT speed tester...
(You will need to open a document program to copy and paste the results, if you need a record for future reference)
For quick check, for your personal info, My Broadband Speed Checker, as recommended by Plusnet.
  (however, this does not save results after you have logged off/shut down your computer.... advise opening a document file to copy and paste results as above)
To check your speed with other servers, (anywhere in the world if you want to) www.speedtest.net ; this is just as accurate as the My Broadband Speed tester above, despite several people on here rubbishing it.... ( I have proof over 3 weeks using all three) this site also saves EVERY Speed test you ever do..... I have some going back 2 years .. ) so even if you don`t approve of it, it will hold a record for your future reference... 
Oh by the way, I am over 2 km from my exchange, so do not get very high speed anyway...

[#6]

shutter you a static ip then if you can view back 2 years on speedtest.net

[#7]

it does save the test as a cookie, but Gerry is paranoid and clears his every time, does a malware run etc, so no record, mine go back to last June

[#8]

Not so much paranoid..... just can`t see any point in having someone else using my computer for their references.....filling my hdd with rubbish.  (am quite capable of doing that meself !  :D)

[#9]

Quote from: shutter

For quick check, for your personal info, My Broadband Speed Checker, as recommended by Plusnet.   (however, this does not save results after you have logged off/shut down your computer.... advise opening a document file to copy and paste results as above)

Wrong! It saves the results for up to a year - unfortunately at present at the end of a year it wipes the lot due to a current bug. Unless as pierre_pierre pointed out you are paranoid and you delete the link to your previous results!