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Four route sources visible: `S*` for the default route, `C` for the directly-connected subnets, `L` for the router's own interface addresses, and two more `S` statics pointing to the same next-hop. Read the syntax carefully — each line tells you where traffic goes and how confident the router is.
| Field | Meaning |
|---|---|
| Code (S, C, L, O, etc.) | Route source |
| [1/0] | Administrative distance / metric |
| via 10.10.20.2 | Next-hop IP address |
| directly connected | No next-hop — destination is on-link |
| on GigabitEthernet0/1 | Egress interface |
| * | Candidate default route |
`[1/0]` — the first number is AD, the second is metric. Both matter. AD breaks ties between route sources; metric breaks ties within the same source. A static route to the same destination with `[1/5]` and `[1/10]` — the one with the lower metric wins.
! 1. Next-hop only — router figures out the egress interface via recursive lookupip route 172.16.5.0 255.255.255.0 10.10.20.2! 2. Exit-interface only — useful on point-to-point links (serial, /30 or /31 Ethernet)ip route 172.16.6.0 255.255.255.0 gigabitEthernet0/2! 3. Both next-hop and exit-interface — most explicit, recommended for Ethernet multipointip route 172.16.7.0 255.255.255.0 gigabitEthernet0/2 10.10.20.2
On point-to-point links, exit-interface-only works fine — there's only one possible neighbor. On Ethernet multipoint links (multiple destinations reachable on the same segment), you must supply the next-hop, or specify both. Without it, the router has no way to ARP for the destination.
Exit-interface-only statics on Ethernet are a classic misconfiguration. The router treats every destination on that interface as "directly connected," ARPs for each destination IP individually, and may or may not get an answer. Traffic that should route gets dropped instead.
Finish the lesson once you have worked through the material. This awards ★ 30 XP.