this is just a lab! this is lab 3-3 on page 137 in the attached pdf (old ccnp route lab manual)
Based on my understanding, summary-address command is used on ASBR's to advertise only a single LSA Type 5 which summarizes all subordinate subnets that had been previously redistributed into OSPF from other routing sources
The lab asks us to distribute a default route from R1 (see lab 3-3 in the attached pdf on page 137) into area 0, and the command "default-information originate always" works as expected.
However, I am experimenting with the "summary-address" command, so after redistributing a connected subnet (172.30.30.1/30) using "redistribute connected subnets" command, I throw a "summary-address 0.0.0.0 0.0.0.0" into my ospf configuration expecting that R1 stops redistributing that connected subnet (172.30.30.1/30) into area 0 and then advertises a single LSA type 5 with a default route.
The result is that R1 creates a default route to "null" within its own routing table, stops redistributing 172.30.30.1/30 but does not advertises an LSA Type 5 with a default route into area 0. Am I understanding something wrong?