CCNA 200-301 v1.1 quick lookup
Routing codes and administrative distances
The protocol codes shown by the routing table and the default administrative distances they imply.
Protocol numbers and portsIPv4 masks and block sizesIPv6 address spaceRouting codes and administrative distancesSyslog levels and thresholdsProtocol defaults and timers
From The routing table — the same block lives in that article
Routing table protocol codes
| Code | Source | Meaning |
|---|---|---|
| C | Connected | Network of an up interface |
| L | Local | The interface's own /32 host route |
| S | Static | Manually configured |
| S* | Static default | Candidate gateway of last resort |
| O | OSPF | Intra/inter-area link-state route |
| O IA | OSPF inter-area | Route learned from another OSPF area |
| D | EIGRP | Internal EIGRP route |
| D EX | EIGRP external | Redistributed into EIGRP |
| R | RIP | Distance-vector RIP route |
| B | BGP | Border Gateway Protocol route |
From The routing table — the same block lives in that article
Default administrative distances
| Source | AD | Notes |
|---|---|---|
| Connected | 0 | Cannot be beaten — same prefix always wins |
| Static | 1 | Floating statics raise this deliberately |
| eBGP | 20 | External BGP (context) |
| EIGRP (internal) | 90 | |
| OSPF | 110 | |
| RIP | 120 | |
| iBGP | 200 | Peers within the same AS (BGP interior sessions) |
| Unreachable | 255 | Route is never installed |
Lower is preferred — but AD compares candidate routes for the SAME prefix, never for different prefixes.