单项选择题
A. Internet Protocol address
B. Media Access Control address
C. Packet Layer Proto col address
D. Network Service Access Point address
E. Authority and Format Identifier address
单项选择题 What is the default metric used on IS -IS routers for each interface?（）
单项选择题 Which packet type is used to ackno wledge LSPs on point - to - point links and to request missing pieces of information in the IS - IS link -state database?（）
单项选择题 What is periodically sent by a DIS on a LAN to ensure that all adjacent neighbors' IS - IS link - state databases are synchronized?（）