Refer to the exhibit.

Route tagging with a route map is the correct redistribution loop-prevention method. In a design with mutual redistribution between OSPF and IS-IS, a route learned from one domain can be redistributed into the other domain and then fed back into the original domain at another redistribution point. This creates route feedback, suboptimal routing, or loops. Cisco routing design commonly prevents this by tagging routes at the point of redistribution and then filtering or denying routes with that tag when they are seen again at another redistribution boundary. A route map can set the tag during redistribution and match the tag on the reverse redistribution direction. Changing administrative distance may influence local route selection, but it does not reliably prevent feedback throughout the network. Stub areas reduce external LSA scope in OSPF, but they do not solve a multipoint redistribution loop between OSPF and IS-IS. Prefix filtering can work, but tagging scales better and preserves route identity across redistribution points. Reference topics: route redistribution, route tagging, route maps, OSPF, IS-IS, loop prevention.