it depends on the application. O/S doesn't have any relation with network Gateway.

Gateway is for routing packets from one segment ( Subnet ) to another.

for example:

if my AIX IP Address is configured 172.16.100.169 and I want to reach 10.10.10.10

then my gateway (whatever IP address given by network admin) should know how to reach 10.10.10.10

that's all.