The specification says:

If the DNS request returns no verified hosts in SRV records, no SRV records at all, or a DNS error happens, the driver:

• MUST NOT change the topology
• MUST NOT raise an error
• SHOULD log this situation, including the reason why the DNS records could not be found, if possible
• MUST temporarily set rescanSRVIntervalMS to heartbeatFrequencyMS until at least one verified SRV record is obtained.

 
The driver does not implement this behavior, nor the prose test that asserts it.