What’s the difference?
router ospf 1
network 0.0.0.0 0.0.0.0 area 0
vs.
router ospf 1
network 0.0.0.0 255.255.255.255 area 0
Both add all existing interfaces into area 0 and all later added interfaces also. Both statements are valid.
For the default route it seems the same:
ip route 0.0.0.0 0.0.0.0 f1/1
vs.
ip route 0.0.0.0 255.255.255.255 f1/1
both work, sending traffic to the default gatewayf f1/1.
What IOS does not permit is a mixture for example.:
0.0.0.0 0.0.255.255
or
0.0.0.0 0.255.255.255
SW1(config)#ip route 0.0.0.0 0.0.255.255 f1/1
%Inconsistent address and mask
Both statements are the same. Since both have the same logical „AND“ing result for the host part, namely „0“.
0 0 0 0 0 0 0 0
1 1 1 1 1 1 1 1
———————-
0 0 0 0 0 0 0 0
vs.
0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0
———————-
0 0 0 0 0 0 0 0