R1 as an NTP server must have:
- NTP authentication enabled
- NTP packets sourced from Interface loopback 0
- NTP stratum 2
- NTP packets only permitted to client IP 209.165.200.225 How should R1 be configured?
A.ntp authenticate正确答案A
Ntp authentication-key 2 md5 CISCO123
Ntp source Loopback0
Nntp access-group server-only 10
Ntp master 2
!
Access-list 10 permit 209.165.200.225 B.ntp authenticate
Ntp authentication-key 2 md5 CISCO123
Ntp source Loopback0
Ntp access-group server-only 10
Ntp stratum 2
!
Access-list 10 permit udp host 209.165.200.225 any eq 123 C.ntp authenticate
Ntp authentication-key 2 sha1 CISCO123
Ntp source Loopback0
Ntp access-group server-only 10
Ntp master 2
!
Access-list 10 permit udp host 209.165.200.225 any eq 123 D.ntp authenticate
Ntp authentication-key 2 md5 CISCO123
Ntp interface Loopback0
Ntp access-groud server-only 10
