Currently cache duration is controlled by the hard-coded value NotaryHTTPServer.CACHE_EXPIRY. To alter the defaut of 24 hours you have to edit the code. This is not ideal and we should expose the value so it can be passed as an argument on startup.
The --cache-duration / --cache-expiry argument has been added in version 3.4. There are even docs in doc/advanced_notary_configuration.txt on how to use it!
Currently cache duration is controlled by the hard-coded value NotaryHTTPServer.CACHE_EXPIRY. To alter the defaut of 24 hours you have to edit the code. This is not ideal and we should expose the value so it can be passed as an argument on startup.