The nslookup program operates interactively.
When you start the program from the UNIX command line, it uses the /etc/resolv.conf file to
locate a name server, and initially directs its queries at that server.
Default Server: dns.class.com
Addresses: 126.96.36.199, 188.8.131.52,
184.108.40.206, 220.127.116.11, 18.104.22.168,
22.214.171.124, 126.96.36.199, 188.8.131.52,
184.108.40.206, 220.127.116.11, 18.104.22.168,
22.214.171.124, 126.96.36.199, 188.8.131.52,
184.108.40.206, 220.127.116.11, 18.104.22.168
Evidently, Microsoft operates quite a few machines under the name www.microsoft.com.
You may see the phrase non-authoritative answer
in the output from nslookup.
This phrase means that
obtained the information from a server cache, rather than by consulting an authoritative source such as an
or secondary server
authoritative server: A primary or secondary server for a zone is called an authoritative server when it obtains its information directly
from data files describing the zone.
secondary server: In addition to its primary server, a zone may have one or more secondary servers. A secondary server provides an
alternative source for information on the zone.