The RIPv1 Auto Redistributed Static /32 Host Route

Sample Network Topology

RT1#conf t
Enter configuration commands, one per line.  End with CNTL/Z.
RT1(config)#router rip
RT1(config-router)#net 192.168.1.0
RT1(config-router)#net 192.168.2.0
RT1(config-router)#end
RT1#
======================================================================
RT2#conf t
Enter configuration commands, one per line.  End with CNTL/Z.
RT2(config)#router rip
RT2(config-router)#net 192.168.2.0
RT2(config-router)#net 192.168.3.0
RT2(config-router)#net 192.168.4.0
RT2(config-router)#exit
RT2(config)#
RT2(config)#ip route 192.168.2.3 255.255.255.255 fa1/0
RT2(config)#
======================================================================
RT1#sh ip route

Gateway of last resort is not set

R    192.168.4.0/24 [120/1] via 192.168.2.2, 00:00:11, Serial0/0
C    192.168.1.0/24 is directly connected, FastEthernet1/0
     192.168.2.0/24 is variably subnetted, 2 subnets, 2 masks
R       192.168.2.3/32 [120/1] via 192.168.2.2, 00:00:11, Serial0/0
C       192.168.2.0/24 is directly connected, Serial0/0
R    192.168.3.0/24 [120/1] via 192.168.2.2, 00:00:11, Serial0/0
RT1#

This behavior is documented in Cisco Press - Troubleshooting IP Routing Protocols.