Or at least, that's what I think is happening. There doesn't appear to be a debug command for this, or to see if something is in the routing table.

I'm testing out this setup in Packet Tracer. I have 3 routers and a webserver

From left to right, you have: Webserver -> Router1 -> Router2 -> Router3

Router1 and Router2 can succesfully ping WebServer. Router3 cannot.

Router2 has a default gateway set, to send all not-recognized data through its serial interface to Router1.

Like this: ip route 0.0.0.0 0.0.0.0 Serial 0/0/1 Serial 0/0/1 being the connection to Router1

Router2 and Router3 have OSPF configured. From their "show run":

Router2:

router ospf 1
 log-adjacency-changes
 passive-interface Serial0/0/1
 network 10.1.1.0 0.0.0.3 area 0
 default-information originate
!

Router3:

router ospf 1
 log-adjacency-changes
 network 10.1.1.0 0.0.0.3 area 0
 passive-interface FastEthernet0/0
!

I was under the assumption that setting default-information originate on Router2 would give Router3 the needed information. What's going wrong here?

The interfaces are up. Ip addresses are with mask-range, clock rate is set at correct end. I don't know what else to check.