EIGRP - Network command syntax
When issuing the EIGRP network command to advertise a directly connected network, it is not necessary to specify the network address with a wildcard mask. It is possible to use a host address when configuring the command. However, when this is done, the command reverts to the network address.
For example, if you issue a network command using the host address 10.10.10.55 with a subnet mask of 255.255.255.0, you get the following results:
R1(config)#router eigrp 1 R1(config-router)#network 10.10.10.55 255.255.255.0 R1(config-router)#exit R1(config)#exit R1#show run | section eigrp router eigrp 1 network 10.10.10.0 0.0.0.255 R1#
Note that the network command that ends up in the running configuration reverts to the network address of that particular host and wildcard mask combination.