Routing question on a Cisco router

Question

I have a quick question regarding routing (on Cisco routers If I need to be specific). It's related to an issue I'm looking at for a client.

They have an application being hosted on a server (accessible from outside) and the routing appears erratic at times. Suppose the gateway for that network has an IP address of 203.200.10.61/25 assigned on the router .

But, there's a static route configured for the 203.200.10.0/24 network to 203.200.10.1 which is assigned to an interface on another router (which we nor the client have no control over hosted on their network). Both routers have default routes configured by the way. It's discontiguous for reasons I know not and their network design could probably use some work.

But my question is - if I have a packet destined to 203.200.10.107, will it use the static route to 203.200.10.1 on another router or will it route through the local 203.200.10.61/25 interface on the router?

Based on administrative distance, the interface with the 203.200.10.61/25 should take precedence over the static route if I'm not mistaken?

Answer 1

Yes, directly connected interface have a higher priority than a static route. Have a look at this table:

You can use the command show ip route and you will see, that the static route is not in the routing table because a directly connected entry is taking its place for this subnet.

Usually static routes are in place as a 'backup' path. Once the interface with the network goes down, the static route can take over and route the traffic to another path. But this is more old-style thinking and routing protocols do this much better than a static configuration would.

Answer 2

The directly connected network (administrative distance of 0) should take precedence over the static route (administrative distance of 1), unless the static route is set to be followed through policy based routing.

Answer 3

Yes your are correct . Traffic will take route with 203.200.10.61/25 because specific route will take precedence over another route /24 subnet route

General /25 subnet will have priority over /24 subnet .

Basically Administration distance (AD) value is considered when there are multiple routing protocols are configured in router destined to same destination then only according to least AD value the route is chosen among available routing protocols by L3 devices to forward packet to destination .