The resolver would translate this into a request for PTR RRs for 65.0.6.26.IN-ADDR.ARPA. This information is not in the cache, so the resolver would look for foreign servers to ask. No servers would match, so it would use SBELT again. (Note that the servers for the ISI.EDU domain are in the cache, but ISI.EDU is not an ancestor of 65.0.6.26.IN-ADDR.ARPA, so the SBELT is used.)
Since this request is within the authoritative data of both servers in SBELT, eventually one would return:
+---------------------------------------------------+
Header | OPCODE=SQUERY, RESPONSE, AA |
+---------------------------------------------------+
Question | QNAME=65.0.6.26.IN-ADDR.ARPA.,QCLASS=IN,QTYPE=PTR |
+---------------------------------------------------+
Answer | 65.0.6.26.IN-ADDR.ARPA. PTR ACC.ARPA. |
+---------------------------------------------------+
Authority | <empty> |
+---------------------------------------------------+
Additional | <empty> |
+---------------------------------------------------+