Which three are advantages to creating multiple areas in OSPF? (Choose three.)

A.
less frequent SPF calculations

B.
fewer hello packets

C.
smaller routing tables

D.
reduced LSU overhead

E.
fewer adjacencies needed

Explanation:
OSPF routers within an area only need to know about other routers within their own area, not
outside their area, and all OSPF routers within a given area share the same link state database.
This keeps the routing tables small enough to prevent processing bottlenecks from occurring.
Also SPF only needs to calculate paths to routers within that area.
If a router receives an LSA with old information then it will send a LSU to the sender to update the
sender with the newer information. The Link State Update (LSU) holds the LSAs. Instead of
sending multiple LSUs the ABR / ASBR summarizes a route and sends only one LSU-.

Note: The LSA has a 30 minute timer that causes the router to send an LSU to everyone on the
network once it ages out.