A network of five nodes is using symmetrical keys to securely transmit data. How many new keys
are required to re-establish secure communications to all nodes in the event there is a key
compromise?

A.
5

B.
10

C.
20

D.
25

Explanation:
Per Sybex CISSP Study Guide 3rd Edition (page #314)
total # of symmetrical keys needed is expressed as:
[number of participants * (number of participants-1)]/2
s/b B. 10 not A. 5