There is LAN segment with R1,R2,R3 running EIGRP. R3 is configured as stub. R1 and R2 are connected to other LAN segment. R1's connection to that segment is goin down. R1 send update that it has no longer that prefix. R3 receives it and let's assume that it has not feasible successor for that route. Will R3 query both R1 and R2 ? Does stub functionality changes this behavior or not ?
The EIGRP Stub router feature has these properties:
1.) For any query received, a stub router replies immediately with "destination unreachable" without propagating the query further
2.) Any network that is learned via EIGRP a stub router is not advertised to any further neighbor
3.) Only a specific subset of locally generated or connected networks is advertised by a stub router to its neighbors (the options are connected, summary, static, any combination thereof, or none)
4.) Neighbors of stub routers do not send any queries to stub routers
However, by itself, an EIGRP Stub feature does not prevent the stub router itself to send queries.
Imagine a simple dual-homed stub router connected to two different routers at the HQ site, one of them being significantly faster and therefore preferred. Now, imagine this faster link going down. The stub router will most certainly lose the successor for majority of its networks and the neighbor at the slower link may not be identified as the feasible successor because of the relation between the feasible and reported distance. If the stub router was now prevented from sending queries, it would not use the slower backup link to reach the networks at HQ. However, there is no limitation on sending queries, even by a stub router. In this case, the stub router will send a query to its neighbor on the slower link and after it replies, the stub router will identify it as the backup route to destinations at HQ.