When installing, did you select DSL as your Internet choice. If so, the system is trying to use PPoE rather than straight ethernet. Boot the system, open a terminal window and type ipconfig eth0 up then dhcpcd eth0 , and tell us what happens.
Did you want to know what LDAP & NIS stand for?
What they are used for?
Why someone would use them?
Please explain that part a little more.