Which two items best describe a Cisco IOS IP SLA responder?

Which two items best describe a Cisco IOS IP SLA responder? (Choose two.)

A.
required at the destination to implement Cisco IOS IP SLA services

B.
improves measurement accuracy

C.
required for VoIP jitter measurements

D.
provides security on Cisco IOS IP SLA messages via LEAP or EAP-FAST authentication

E.
responds to one Cisco IOS IP SLA operation per port

F.
stores the resulting test statistics

Explanation:
The Cisco IOS IP SLAs Responder is a component embedded in the destination Cisco routing
device that allows the system to anticipate and respond to Cisco IOS IP SLAs request packets.
The Cisco IOS IP SLAs Responder provides an enormous advantage with accurate
measurements without the need for dedicated probes and additional statistics not available via

standard ICMP-based measurements. The patented Cisco IOS IP SLAs Control Protocol is used
by the Cisco IOS IP SLAs Responder providing a mechanism through which the responder can be
notified on which port it should listen and respond. Only a Cisco IOS device can be a source for a
destination IP SLAs Responder. Fr IP SLAs VoIP UDP Jitter Operations your networking devices
on both ends of the connection must support Cisco IOS IP SLAs.
Reference:
http://www.cisco.com/en/US/docs/ios/12_4/ip_sla/configuration/guide/hsoverv.html