I am running Firefox ESR 60.4.0. I have noticed that if I load a page, close the browser, reopen the browser and load the same page, duplicate DNS queries are sent, even at intervals less than the TTL or default cache expiration period. This behavior does not appear to be affected whether or not I change my privacy settings to clear the history when the browser closes. I am trying to understand if this repetition is normal, and where (if anywhere) in the file system the Firefox DNS cache is stored.