Which Junos operational command displays all operational IS-IS neighbors?

A.
show isis interface

B.
show isis database

C.
show isis neighbors

D.
show isis adjacency

Explanation:
Assuming that all the routers are correctly configured for IS-IS, you can verify which neighbors are adjacent and able to exchange IS-IS data. In addition, you can examine the set of routes installed in the forwarding table to verify that the routing protocol process (rpd) has relayed the correct information into the forwarding table.

show isis adjacency brief
user@host> show isis adjacency brief
IS-IS adjacency database:
Interface System L State Hold (secs) SNPA
so-1/0/0.0 1921.6800.5067 2 Up 13
so-1/1/0.0 1921.6800.5067 2 Up 25
so-1/2/0.0 1921.6800.5067 2 Up 20
so-1/3/0.0 1921.6800.5067 2 Up 19
so-2/0/0.0 1921.6800.5066 2 Up 19
so-2/1/0.0 1921.6800.5066 2 Up 17
so-2/2/0.0 1921.6800.5066 2 Up 20
so-2/3/0.0 1921.6800.5066 2 Up 20
so-5/0/0.0 ranier 2 Up 17

show isis adjacency detail
user@host> show isis adjacency detail
toothache
Interface: fe-0/0/1.0, Level: 1, State: Up, Expires in 26 secs
Priority: 64, Up/Down transitions: 1, Last transition: 00:19:34 ago
Circuit type: 3, Speaks: IP, CLNS, MAC address: 0:12:0:34:0:56
Topologies: Unicast
Restart capable: Yes
LAN id: pro1-a.02, IP addresses: 192.168.37.69

toothache
Interface: fe-0/0/1.0, Level: 2, State: Up, Expires in 26 secs
Priority: 64, Up/Down transitions: 1, Last transition: 00:26:11 ago
Circuit type: 3, Speaks: IP, CLNS, MAC address: 0:12:0:34:0:56
Topologies: Unicast
Restart capable: Yes
LAN id: pro1-a.02, IP addresses: 192.168.37.69

show isis adjacency extensive
user@host> show isis adjacency extensive
isis2
Interface: sr1.0, Level: 3, State: Up, Expires in 25 secs
Priority: 0, Up/Down transitions: 16, Last transition: 00:00:01 ago
Circuit type: 3, Speaks: IP
Restart capability: Yes
IP addresses: 123.456.36.18
Transition log:
When State Event Down Reason
Fri Jun 29 17:32:26 Up Seenself
Fri Jun 29 17:32:42 Down Interface Down 3-Way Handshake Failed
Fri Jun 29 17:32:52 Up Seenself
Fri Jun 29 17:33:19 Down Level Mismatch 3-Way Handshake Failed
Fri Jun 29 17:33:25 Up Seenself
Fri Jun 29 17:33:43 Down Level Mismatch
Fri Jun 29 17:33:49 Up Seenself
Fri Jun 29 17:35:40 Rejected Error
Fri Jun 29 17:36:12 Up Seenself
Fri Jun 29 17:36:47 Down Interface Down 3-Way Handshake Failed
Fri Jun 29 17:36:59 Up Seenself