Which two of these multicast deployments are most susceptible to attacks from unknown sources？（）

单项选择题WhatisthedefaultvalueoftheSPTthresholdinCiscorouters？（）

A. 0
B. 1
C. 2
D. 4
E. 16
F. infinity

多项选择题Refer to the exhibit. Which two statements are correct regarding the creation of a multicas tdistribution tree？ （）

A. Each router determines where to send the JOIN request.
B. The tree will be built based on the IP address of the E2 interface on router E
C. The best path to the source will be discovered in the unicast routing table on router B
D. The best path to the source will be discovered in the unicast routing table on router C
E. The best path to the source will be discovered in the unicast routing table on router E

单项选择题TowhichofthesedoesIPmulticastsendpackets？（）

A. a single host
B. a subset of hosts
C. all hosts sequentially
D. all hosts simultaneously

单项选择题Whichoftheseportsdoessyslogusetosendmessagestoasyslogserver？（）

A. TCP 502
B. TCP 514
C. TCP 520
D. UDP 502
E. UDP 514
F. UDP 520

单项选择题WhichoftheseisabenefitofESM？（）

A. supports multiple MIBs
B. includes NetFlow， NBAR， and IP SLA software subsystems
C. includes NetFlow， syslog， and IP SLA software subsystems
D. includes a predefined framework for filtering and correlating messages
E. supports two logging processes so output can be sent in standard and ESM format