A. Never use passive interfaces.
B. Use NSSA areas from the core down.
C. Use totally stub areas to stop type 3 LSAs.
D. Use the lowest Ethernet interface IP address as the router ID.
E. Tune OSPF timers to enable OSPF to achieve quicker convergence.

A. Server-to-server traffic always remains in the core layer.
B. The recommended practice is for the core infrastructure to be in Layer 3.
C. The boundary between Layer 2 and Layer 3 should be implemented in the aggregation layer.
D. The Cisco Express Forwarding hashing algorithm is the default, based on the IP address and Layer 4 port.
E. Core layer should run BGP along with an IGP becauseiBGP has a lower administrative distance than any IGP.