I'm getting ready to recertify for CCNA for a job I might be getting and I'm kinda confused on something. This is all in a router sim, so that may be why it's not working. Anyways I setup this diagram to practice routing protocols. i enabled rip on all of the routers and told it which networks to advertise. but for some reason WS4 can't ping WS3 w/o having a static route setup on rtr-central. from ws4, i can ping all the way up to the serial interface on the right hand side of rtr-central. the other serial int on the router drops it. both links are up/up so im not sure. like i said making a static route on rtr-central to 10.100.30.0 solves the problem, but i'm not exactly sure why.
so if anyone can point me in the right direction id appreciate it