How does OSPF advertise a network ??

[ipsec]

Hello,

The Router R1 has got 2 directly connected Network say 172.16.0.0 /24 and 192.168.5.0 /24. And the network 10.0.0.0 /24 is being advertised by the neighbor router. Both Eigrp and OSPF is running on the router.

The below is the relevant config:
!
router eigrp 100
network 172.16.0.1 0.0.0.0
network 192.168.5.1 0.0.0.0
no auto-summary
!
router ospf 1
log-adjacency-changes
network 172.16.0.0 0.0.0.255 area 0
network 192.168.5.0 0.0.0.255 area 0
!

************

Gateway of last resort is not set

172.16.0.0/24 is subnetted, 1 subnets
C 172.16.0.0 is directly connected, Serial2/0
C 192.168.5.0/24 is directly connected, Loopback0
10.0.0.0/8 is variably subnetted, 2 subnets, 2 masks
D 10.0.0.0/24 [90/2297856] via 172.16.0.2, 00:16:24, Serial2/0
O 10.0.0.1/32 [110/65] via 172.16.0.2, 00:17:42, Serial2/0

Why there are 2 routes to network 10.0.0.0 with 2 different masks ?. I am not able to undertsand that how OSPF is advertising the network as /32 mask ?.

[user123]

If 10.0.0.1 is a loopback interface, OSPF will advertise it as a host (/32) address. You can use the ip ospf network point-to-point in the interface configuration mode to cause OSPF to advertise the subnet mask configured on the interface.

If 10.0.01 is on a frame-relay interface configured with ip ospf network point-to-multipoint, OSPF will advertise the host address in addition to the network.

[ipsec]

Thanks so much for your clarification.