Can any body tell me what is difference between Default route information origin,Default gateway and ip route 0.0.0.0 0.0.0.0.a.b.c.d
and how it select the route.
Thanks in Adv.
Default gateway is usually used on switches that are not L3 switches/routers or on "hosts". It just points to a router that "knows" how to get out.
The term "Default Route" usually means "ip route 0.0.0.0 0.0.0.0 x.x.x.x" or "default-information originate". And means, if you don't have a "more specific" route, then send it to x.x.x.x, and that router will take care of it.
"Default-information originate", is the exact same thing as "ip route", except it's sending it through a routing protocol.
If a router learns a default route from another router through a routing process, it will have a cost associated, as well as the administrative distance of the routing protocol. The important information is the AD (administrative distance). When we type the command "ip route" the AD for that route is 1 (unless we change it). If we learn a default route from OSPF, it will have the AD of OSPF (110). So the static will be preferred.
I hope this helps. If your using something other than OSPF, just look at the AD of the routing protocols to figure out the preferred (lowest) one.