单选题
One of the most widely used routing protocols in IP
networks is the Routing Information Protocol (RIP). RIP is the canonical example
of a routing protocol built on the ______ algorithm. Routing protocols in
internetworks differ slightly from the idealized graph model. In an
internetwork, the goal of the routers to forward ______ to various
networks. Routers running RIP send their advertisement about
cost every ______ seconds. A router also sends an update message whenever an
update from another router causes it to change its routing table.
Routing protocols use different techniques for assigning ______ to
individual networks. Further, each routing protocol forms a metric aggregation
in a different way. RIP takes the simplest approach, with all link costs being
equal ______. Thus it always tries to find the minimum hop route. Valid
distances are 1 through 15. This also limits RIP to running on fairly small
networks.