Explain the following with reference to domain name system(DNS):

Name SERVERS are server programs, which hold
information about the domain tree’s structure and set information. A name
server may cache structure or set information about any part of the domain
tree, but in general a particular name name server has complete information
about a subset of the domain space and pointers to other name servers that can
be used to lead to information from any part of the domain tree

The zone, as indicated in the figure on the next
page, is a subtree of the DNS that is administered separately. A name server
can support multiple zones. Zones are contiguous regions of the name space,
where each can be forked into sub zones. Each of these sub zones can have its
independent management.