‘Resolving DNS’ is the type of DNS service usually referred to when an internet provider talks to their customers about their DNS servers. It is a different type of DNS service to ‘content DNS’.
DNS resolution is the internet service that translates internet server names to numbers and is part of a functioning internet connection. There is nothing difficult about a computer running its own DNS resolver, but you usually rely on your network operator to do so. For your servers, that’s Bytemark!
You can tell nearly all Linux applications which DNS servers to use by editing the file /etc/resolv.conf. By default, we set machines up to use our own DNS servers which are located at these IP addresses:
2001:41c8:2::1
2001:41c8:2::2
80.68.80.24
80.68.80.25
Therefore, your /etc/resolv.conf should look like this:
search yourdomain.co.uk
nameserver 2001:41c8:2::1
nameserver 2001:41c8:2::2
nameserver 80.68.80.24
nameserver 80.68.80.25
Testing Resolving DNS
To test your resolving DNS service you should use the dig tool to ask for a name to be looked up with your system’s default DNS service, i.e.:
# normal "A" record lookup
dig www.manchester.ac.uk
# "MX" record lookup for mail delivery
dig mx manchester.ac.uk
# "NS" record; who's authoratitive for this domain?
dig ns bytemark.co.uk
Timeout
If dig is timing out or taking too long, you can send a DNS query directly to a particular server to check that it is working. This ignores your system’s currently configured DNS settings:
# test Bytemark's name server
dig ns bytemark.co.uk @2001:41c8:2::1
# test Manchester University's name server
dig ns bytemark.co.uk @130.88.13.7