DNS

A records must have a value that is an IP Address

CNAME records can have a domain name like server.domain.co.nz

Interspeed (formerly SOA) updates their records hourly to their nameservers. THIS UPDATE WILL NOT HAPPEN IF THERE IS ANYTHING WRONG WITH ANY OF THE DNS ENTRIES (E.G. DOMAIN NAME IN AN A RECORD). 

For new records you will be able to use them as soon as this happens. For existing records, your DNS server may take a couple of hours to update after that. 

How to find who controls a Domain Name

There is a website http://www.who.is which has a very nice short URL system.

For example to find beweb.co.nz you can just type this in your browser address bar:

who.is/beweb.co.nz