for RIP which is classful routing protocol , means use subnet mask as default
or all networks should have same subnets mask , either subnetted mask would use but same for all networks , i used 10.0.x.0/30, having all the Routers' networks subnet masks same as 10.0.2.0/30, 10.0.3.0/30... so on , and routing protocol was RIP using packet tracer but there no communication could establish ...
simplest
