单项选择题
A. only summarized routes
B. all routes in the network
C. all routes in the backbone
D. No routes are advertised.
单项选择题 You have a Level 1-only router (Router A) in IS-IS area 49.0001. How does Router A learn how to reach prefixes in other areas?（）
单项选择题 There are three routers on a Gigabit Ethernet LAN: Router A, Router B, and Router C. Router A is the Designated Intermediate System (DIS) at Level 1 for that LAN. Router As DIS priority is 64. The LAN is a Level 1-only link. Router D has just been powered up on that same LAN and its DIS priority is 80. Which statement is true?（）
单项选择题 What does the LSP Holdtime field in an IS-IS database indicate?（）