What time and identification do the last-modifield and etag in the http cache refer to?

as above, for example, if I upload files locally to the server, do last-modifield and etag mean that if my local files are modified, will there be a new last-modifield and etag, or will a new one be generated only if there are changes in the server files?

because I have tried it myself, upload the same file, and the second time I request a resource, I will return a 200 status code

Front-end http http-cache
Jul.04,2021

clipboard.png

the above picture is what I combed before, but there is no actual experiment on the client or the server

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MySQL Query : SELECT * FROM `codeshelper`.`v9_news` WHERE status=99 AND catid='6' ORDER BY rand() LIMIT 5
MySQL Error : Disk full (/tmp/#sql-temptable-64f5-1b3591f-2bfbf.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
MySQL Errno : 1021
Message : Disk full (/tmp/#sql-temptable-64f5-1b3591f-2bfbf.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
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