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