R4#sh run | b aaa
!
aaa new-model
!
aaa authentication login default none
aaa authentication login Prob6 group tacacs+ local

!
tacacs-server host 17.57.100.99
tacacs-server directed-request
tacacs-server key MyKey
!
line con 0
 exec-timeout 0 0
 logging synchronous
line aux 0
line vty 0 4
 privilege level 15
 login authentication Prob6
!