According to Nquist 's theorem, the telephone system samples human voice ______ times per second in order to fully represent the characteristics of the voice signal.

Which of the following descriptions about the structure of SIP messages are correct ?

The three routers shown in FIG., In Routerl and Router3 between creating built GRE tunnel , three routers are configured to :
[Routerl]interface Serial 0/2/0
[Routerl-Serial0/2/0]ip address 10.1.1.1 24
[Routerl]interface loopback 0
[Routerl-LoopBack0]ip address l.1.1.1 32
[Routerl]interface Tunnel 0
[Routerl-Tunnel0]source 1 0.1.1.1
[Routerl-Tunnel0]destination 20.1.1.2
[Routerl-Tunnel0]ip address 100.1.1.1 24
[Routerl]ospf
[Routerl-ospf-l]area 0
[Routerl-ospf-l-area-0.0.0.0]network 10.1.1.1 0.0.0.255
[Routerl-ospf-l-area-0.0.0.0]network l.1.1.1 0.0.0.0
Router2:
[Router2]interface Serial 0/2/0
[Router2-Serial0/2/0]ip address 10.1.1.2 24
[Router2]interface Serial 0/2/1
[Router2-Serial0/2/1]ip address 20.1.1.1 24
[Router2]ospf
[Router2-ospf-l]area 0
[Router2-ospf-l-area-0.0.0.0] network 10.1.1.2 0.0.0.255
[Router2-ospf-l-area-0.0.0.0] network 20.1.1.1 0.0.0.255
Router3:
[Router3]interface Serial 0/2/0
[Router3-Serial0/2/0]ip address 20.1.1.2 24
[Router3-Serial0/2/0]quit
[Router3]interface loopback 0
[Router3-Loop Back0]ip address 3.3.3.3 32
[Router3]interface Tunnel 0
[Router3-Tunnel0]source 20.1.1.2
[Router3-Tunnel0]destination 10.1.1.1
[Router3-Tunnel0]ip address 100.1.1.2
[Router3]ospf
[Router3-ospf-l]area 0
[Router3-ospf-l-area-0.0.0.0] network 20.1.1.2 0.0.0.255
[Router3-ospf-l-area-0.0.0.0]network 3.3.3.3 0.0.0.0
Use the command ping-a 1.1.1.1 3.3.3.3 on the Router to check the connectivity, l00% received icmp reply packets.
In the process of upward progress, the following describes the processing of data packets by each router.The correct one is _____ .( Choose one or more )

Which of the following are measurement standards for voice quality ?

Which of the following statements about the SSL VPN operation process is correct is _______ .