First, the distance command is of the form:
distance x.x.x.x w.w.w.w
Where the x's are the prefix, and the w's are the wildcard bits, just like in an access list. This particular distance command would match everything, I think since all of the bits are marked as "don't care." If you only want to affect the route 15.0.0.0/8, then you should use:
distance 150.0.0.0 0.0.0.0 10
instead. Note this is a supernet of a class B network, and IGRP isn't real good a carrying supernets, so.... I'd presume you mean some other network than the one you're showing here.
Second, the distance command sets the admin distance of routes learned from peers matching the address specified. Suppose you did this:
distance 10.1.1.0 0.0.0.255 10
Then the 10.1.1.0/24 route would, on being learned from any IGRP peer, have its distance set to 10. This would mean that if you learned a route 10.1.1.0/24 from RIP, with an admin distance of 120, the IGRP route will be preferred. Of course, that's no so different than normal.
Now, if you put both RIP and IGRP at the same distance, up until very recently, there was no way to tell which would win. It would depend on which route was installed in the routing table last. Recenttly, this has changed, and the routing protocols actually check the default admin distance of the two protocols if the actual admin distance has been set to the same value, and the protocol with the lower default admin distance wins.
Hope this helps.
Russ
