Why unwanted multiple default routes/gateways are being created automatically in the system where Red Hat Enterprise Linux High Availability Cluster is configured ?

Issue

• Default routes are being created automatically in the routing table although they are not created manually by any sysadmins

[root@h1-nsc1 ~]# route
[...]
172.20.0.0      *               255.255.0.0     U     0      0        0 eth3
default         172.17.8.1      0.0.0.0         UG    0      0        0 eth1
default         172.16.8.1      0.0.0.0         UG    0      0        0 eth0
default         172.17.18.1     0.0.0.0         UG    0      0        0 eth1

• So above default routes are not created manually, still can see in route command output.
• Above ips 172.17.8.1, 172.16.8.1, 172.17.18.1 belongs to the swith in the network.