difference beetween ip route and ip default-gateway

Here's a couple of interesting things I learned too. One was a few months ago, trying to get a Catalyst 4500 to work with the ip default-gateway command. I configured the switch exactly as I thought it need to, but it would not connect to it's uplink. Finally, after a bit of reading, I found out that the default-gateway command only works on layer 3 switches and routers with the "no ip routing" command. Another thing is the default network command. I've never seen it used, so I decided to check Cisco's site for an explanation of it. Apparently it's (almost) the same thing as doing ip route 0.0.0.0 0.0.0.0 (next hop ip). Here's the difference:

Cisco wrote:
If you use both the ip default-network and ip route 0.0.0.0 0.0.0.0 commands to configure candidate default networks, and the network used by the ip default-network command is known statically, the network defined with the ip default-network command takes precedence and is chosen for the gateway of last resort. Otherwise if the network used by the ip default-network command is derived by a routing protocol, the ip route 0.0.0.0 0.0.0.0 command, which has a lower administrative distance, takes precedence and is chosen for the gateway of last resort.


So in short, if you have ip routing enable, use either ip default-network or ip route 0.0.0.0 0.0.0.0. If you do not have ip routing enable or are working on a pure switch, use ip default-gateway. Interesting stuff.

Edit: Oh yeah, and another difference is how routing protocols treat either command. It's detailed in the below link.
Source: http://www.cisco.com/warp/public/105/default.html#ipnetwork