port 53 tcp/udp
communication can be tested by telnetting to port 53
host.subdomain.second-level domain.top-level domain.
entire name cannot exceed 255 characters
each subname cannot exceed 63 characters
allowed chracters: A-Z, a-z, 0-9, and "-"
example of reverse lookup zone: 1.168.192.in-addr.arpa (class c)
class a = one octet, class b = two octets
location of dns zone files:
types of records:
A records = hosts
round-robin DNS is achieved by having the same hostname for several different IP addresses.