I have a HP ProCurve A7102DL router which has eth1 and eth2 interfaces. I currently have eth1 set as my WAN and eth2 as my LAN side. My eth2 has three IP address assigned to it which are A.A.A.1, B.B.B.1, & C.C.C.1. The LAN side IP addresses all show up in the routing table correctly as A.A.A.0 255.255.255.0 and so on. My eth1 address is my static IP assigned by my ISP. The IP they assigned is X.X.X.252 with a subnet of 255.255.255.248. That connection shows up in my routing table as X.X.X.248. I was wondering why it is changing the IP address of the connected interface and if this is something I should be concerned with.
The routing table is showing the network-ID, not the interface IP address. (Same as your first case, where your ip is a.a.a.1 and network is a.a.a.0/24).
$ ipcalc 10.0.0.252/29 Address: 10.0.0.252 00001010.00000000.00000000.11111 100 Netmask: 255.255.255.248 = 29 11111111.11111111.11111111.11111 000 Wildcard: 0.0.0.7 00000000.00000000.00000000.00000 111 => Network: 10.0.0.248/29 00001010.00000000.00000000.11111 000 HostMin: 10.0.0.249 00001010.00000000.00000000.11111 001 HostMax: 10.0.0.254 00001010.00000000.00000000.11111 110 Broadcast: 10.0.0.255 00001010.00000000.00000000.11111 111