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Ant3000
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Message 231 of 295

Re: Cannot access BBC or Facebook

I have a question for the more technically minded amongst us...

If Akamai selects it's cdn node based on our IP address / dns then why does it not resolve when we manually change our dns settings directly on our device to google's public dns?

Is it because Akamai is basing it's selection on our IP address and so if this is the case if we were to switch of our home hubs for a while in the hope that we'll be assigned a new IP address when we restarted would this then solve our problem? (Well essentially make it someone else's problem for whoever gets assigned our previous dodgy IP address? )

Or will we always be assigned a dodgy IP address based on the range assigned to our location?
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Ant3000
Contributor
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Message 232 of 295

Re: Cannot access BBC or Facebook

Just logged onto a neighbours bt wifi fon and looked up their IP address - 109.144.191.254

Tesco etc not working for me BUT working on theirs!!!
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Guru
Guru
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Message 233 of 295

Re: Cannot access BBC or Facebook

Just to let you know BTWifi (BT Openzone, BT WiFi public hotspots) will assign client devices a different subnet and IP address to the private BT broadband connection as the BTWifi network is a different as it connects to the network at a different point.

Which is why a website may work when using the BTWifi connection then using the private BT broadband connection.

jac_95 | BT.com Help Site | BT Service Status
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nkjG4NvlQ3LI
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Message 234 of 295

Re: Cannot access BBC or Facebook


@jac_95 wrote:
Just to let you know BTWifi (BT Openzone, BT WiFi public hotspots) will assign client devices a different subnet and IP address to the private BT broadband connection as the BTWifi network is a different as it connects to the network at a different point.

 You're correct, when using the BT FON, BT Wifi or Openzone. A tunnel is established to link you (seperate to the BT customer's traffic) into the BT network.
The DHCP leases for the BT wifi networks are recorded with the login credentials, so you are by no means anonymous or untraceable.

However, if you access a genuine (non BT-FON user that has a direct-from-FON Access Point, you'll usually be sharing their IP)
These Access Points will usually go under the name FON or FON-Free-Internet or similar.
Just like entering FIN the BT way, your access to the FON network is recorded in the radius logs of the FON network, so you are identifiable that way too, even though you share the user's public IP.

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nkjG4NvlQ3LI
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Message 235 of 295

Re: Cannot access BBC or Facebook


Ant3000 wrote:


If Akamai selects it's cdn node based on our IP address / dns then why does it not resolve when we manually change -our dns settings directly on our device to google's public dns?

-
That's because the CDN may look up the ReverseDNS associated to our IP, or they may just use the IP itself without looking at the ReverseDNS. This ReverseDNS is handles by BT, because they own the IP adress blocks and they don't allow customers to set their own Reverse DNS entries, unlike some other IPs do.
EDIT: I should add that this has nothing to do with what DNS you own PC uses for DNS lookups, it's purely a "where are you coming from" sort of question the CDN asks when connections come in. The fact you are using Google DNS to resolve lookups for    bbc.co.uk   has nothing to do with what the CDN does.   / end edit
It's also possible that the CDN that BT link to doesn't get based on IP or Reverse DNS at all, and the problem only happens due to a LAGG or Round-Robin setup going bad on certain routes at certian times, so it seems to affect some IPs and not others.
Note that use of the word "resolve" has very special meaning when taking about DNS, it does not mean " to fix an issue or clear up a problem"  ( it specifially means "to return a IP address poujnted to by a DNS entry) So if you can, try to avoid the use of the word "resolve" in the context of "resolving the problem" or techies are going to get extremely confused if DNS is involved 🙂
Broadly speaking, yes, if you power-cycle your homehub then you are likely to get another different WAN IP, this may or may not help your situation, depending if you get a good or a bad one at that time.  BT will also want to discourage you powerclcyling your routers willy-nilly because if everyone does that all at the same time repeatedly, their RADIUS system may get overloaded and it won't help track down the problem.
I wouldn't try it unless I was absolutely desperate - you can;t find a intermittend problemn until you can make it happen long enough to track it down.  Avoiding it altogether makes it harder to fix. Hobson's Choice. 

 

 

 

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nkjG4NvlQ3LI
Contributor
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Message 236 of 295

Re: Cannot access BBC or Facebook

One interesting thing I've noticed, is that switching to the HomeHub for my DNS (I normally use another ISP's DNS on one of my other lines) is that the lookups are rather slow and quite unpredictable, delay-wise.

 

Using A&A's DNS, I get returns in 21milliseconds, then my router caches the results and gives subsequent lookups in under 1 millisecond. When I cange my PC's DNS to the homehub, 192.168.1.254, the same digs take 61milliseconds at best, at worst 800milliseconds, with a high degree of variability. It appears the Homehub does not cache the results.

 

Anyone else surprised by this or noticed the same problem?

 

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Ant3000
Contributor
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Message 237 of 295

Re: Cannot access BBC or Facebook

Had an email from BT Care today to say that BT Wholesale couldn't find a problem and asking if they could close the issue!!

Anyhow, I emailed back and explained my understanding of the problem with the CDN and to ask whether it would be worthwhile trying to obtain a new IP Address and so that advised resetting the router which I did and received an IP Address location a little closer to home.

Was hopeful that this might of solved the problem however it has not and still having problems accessing the usual suspects of websites.

So in another desperate attempt to solve the problem I've been checking the home hub settings and noticed that although my ipad had been showing a DNS of 192.168.1.254 my homehub actually shows the following -

Primary DNS : 213.120.234.2
Secondary DNS : 213.120.234.34

Could it be that these DNS settings that have been assigned by BT could actually be the problem? Would be interested if anyone else having problems shares these primary and secondary dns?
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nkjG4NvlQ3LI
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Message 238 of 295

Re: Cannot access BBC or Facebook

yes, it's normal your HomeHub would have different DNS settings - it get it's DNS lookups done by DNS server further usptream, and in turn, serves these result to your local devices like your Ipad from it's own LAN IP address, 192.168.1.254.

For example, my HomeHub's settings are:

TCP/IP settings
Broadband network IP address: 86.132.215.48
Default gateway: 217.32.144.70
Primary DNS: 213.120.234.58
Secondary DNS: 62.6.40.178

 

and, other than the extremely slow DNS lookups compared to other providers, I have no total failures to connect to BBC and Ebay, only slow responses to DNS lookups and the odd page that fails to load fully. On Tesco.com I have no problems at all.

Last night I had no symptoms except at epak times, where everythign gets a bit slow on my BT line.

 

If I set my PCs DNS to another ISP's DNS server, I get fast lookups, but the same slowness loading some websites like BBC and Ebay when I use my HomeHub as the default gateway for my PC. Changing my defualt gateway to another ISP the slowness goes away instantly.

 

It's prpbably that the slow responses I describe are characteristic of a low-spec DNS servers system or one that is overloaded, probably nothing to do with the "BBC/Tesco/Ebay/Amazon doesn't work" reports, but it's an unusual observation nontheless. I would have assumed if the BT DNS servers were slow, the HomeHubs could cache results for a few minutes at least, reducing the load, but from my  digs  this does not seem to be happening.

 

I get a 21ms non-cached response from another ISP's DNS over an ADSL2+ line, but the best BT can do is 61ms over a 80/20 FTTC line syncing at 80/20, and none of the BT lookups are cached on my local device even for a few seconds. Puzzling.

 

 

EDIT: I don't have the BT's Cameron Censorhip turned on -  do you? I doubt it would make a difference is a well set-up network, but clearly something is well amiss, so that's maybe another factor we should be looking at.

 

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Ant3000
Contributor
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Message 239 of 295

Re: Cannot access BBC or Facebook

I'm growing convinced that the bbc, amazon, facebook etc problem is due to the content delivery network.

Whether this is relative to IP Addresses or DNS Servers or Default Gateways I'm not sure? Is it possible that all having problems share these settings? If so can BT assign us new ones?

Ps nkj.... - I don't have parental controls set up and have never activated them
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Ant3000
Contributor
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Message 240 of 295

Re: Cannot access BBC or Facebook

I'm growing convinced that ours in a content delivery network problem but whether that relates to IP address, Default gateway or DNS settings I'm not sure?

Is it possible we all share some similarities between these settings?

Ps - I've never activated BT's parental controls
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