单选题In IS-IS, how long will the restart helper keep the restarting router in the up state?（）A until the hello dead timer expiresB until the restart duration timer expiresC until the restarting router sets the down bitD until the restart helper sends out th
题目
单选题
In IS-IS, how long will the restart helper keep the restarting router in the up state?（）
A
until the hello dead timer expires
B
until the restart duration timer expires
C
until the restarting router sets the down bit
D
until the restart helper sends out three CSNPs