EDNS0 Client Subnet topology load balancing

This question applies to V.15.1.10.4 DNS and LTM

 

An institution in higher ed, with four campuses, requires a finer degree of control over load balancing applications across two data centers.  Until recently, topology records based on LDNS source IP was sufficient. Due to reasons, this strategy no longer works well for a subset of applications.  

 

I would like to use EDNS0 Client Subnet for select Wide-IPs. The F5 documentation is clear about how to implement this. The documenation also clearly states [emphasis mine], "...the system uses the edns0 client subnet option (if one exists) instead of the source address, when using topology load balancing....if the query does not contain a client subnet option, the system falls back to the source address."

 

However, what isn't clear is what will happen to a DNS query that contains the EDNS0 Client Subnet record, but the source subnet does not fall into one of the four campus subnet topology records.  Will the system still attempt to fall back to source address?