PPP DNS Addresses
Availability
On services that use PPP to connect - which is usually all ADSL and VDSL services.
Information
Typically, your computer will obtain an IP address details from your DSL router, this will also include which DNS servers to use. Typically, the DSL router will give itself as the DNS server and then the router will perform the DNS lookups for you. The DNS servers that the router will use is typically the ones gived to it from the ISP when it logs in.
By default we will provide our normal DNS servers:
217.169.20.20 217.169.20.21
However, you can override this if you like by putting IP addresses here.
Why?
This gives some control over the DNS servers that your computers will use, which is useful if you want to use third party DNS servers that offer adult filtering services - such as OpenDNS.
Problems
Filtering systems are often easy to bypass - and the method described here can be bypassed by simply overriding the DNS servers on the computer.
Many of the services that offer filtering also offer a way to check that they are being used. eg OpenDNS will tell you on their setup pages.