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**Paul** · 12-06-2006, 16:25

To quote from one of our articles ;

Transparent Proxy

Your PC does a dns lookup of the destination servers IP using its own (locally) defined dns servers.
It sends the http request on tcp port 80 to the destination servers IP address.
This request is intercepted by NTL's routers and re-directed to one of a group of transparent proxy [cache] servers - the decision on which proxy server gets used is based on the requested domains IP address.
The chosen proxy server checks if it has a valid copy of the requested page in its cache (using the domain name, not IP address).
If the proxy has the page it returns it directly back to the client, Job done.
If the proxy does not have the page it does a dns lookup of the requested domain using it's own defined dns servers.
The proxy sends the http request on tcp port 80 to the destination servers IP address.
This request is routed over the network direct to the destination servers IP.
The requested page is then returned, by the destination server, directly back to the proxy server.
The requested page is then returned, by the proxy server, direct to the client.

As you can see from point 6, they use their own DNS servers which are obviously the ntl dns servers, so if they are not working, your browsing will fail at that point, whatever dns servers *you* have set.

12-06-2006, 16:25	#12
Paul Dr Pepper Addict Cable Forum Admin Join Date: Oct 2003 Location: Nottingham Age: 63 Services: Zen & YouFibre FTTP, Sky Q TV, Sky Mobile, Flextel SIP Posts: 31,308	Re: Transparent Proxiy Cache And Ntl To quote from one of our articles ; Transparent Proxy Your PC does a dns lookup of the destination servers IP using its own (locally) defined dns servers. It sends the http request on tcp port 80 to the destination servers IP address. This request is intercepted by NTL's routers and re-directed to one of a group of transparent proxy [cache] servers - the decision on which proxy server gets used is based on the requested domains IP address. The chosen proxy server checks if it has a valid copy of the requested page in its cache (using the domain name, not IP address). If the proxy has the page it returns it directly back to the client, Job done. If the proxy does not have the page it does a dns lookup of the requested domain using it's own defined dns servers. The proxy sends the http request on tcp port 80 to the destination servers IP address. This request is routed over the network direct to the destination servers IP. The requested page is then returned, by the destination server, directly back to the proxy server. The requested page is then returned, by the proxy server, direct to the client. As you can see from point 6, they use their own DNS servers which are obviously the ntl dns servers, so if they are not working, your browsing will fail at that point, whatever dns servers you have set. __________________ Baby, I was born this way.