单项选择题
By default, how often does a router running IGRP send its complete routing table to its neighbors?（）
A. Every 5 minutes B. Every 90 seconds C. Every 60 seconds D. Every 30 seconds
单项选择题 On what kinds of networks does OSPF elect a backup designated router?（）
多项选择题 Which of the following are characteristics of OSPF areas?（）
多项选择题 What are some of the characteristics of the OSPF routing protocol?（）
