In the world of computing, every programmer is taking the initiative to have continuous learning. This is to ensure that they will stay up-to-date of the current events and latest happenings in the industry. Besides, this is a nice way of refreshing the mind of what new and old.
For instance, there is the If-Modified-Since request HTTP header. This is making conditional request in which the server sends back the resource requested with 200 status, only if it’s been last updated after the date given.
In case the request hasn’t been modified, then the response is going to be a 304 without anybody. The Last-Modified response header from past request holds the date of the last time that it was modified. In comparison to If-Unmodified-Since, the If-Modified-Since could be used only with a HEAD or GET.
If ever that it was used in conjunction with an If-None-Match, then it will be ignored. Well unless the server has no support to If-None-Match.
As a matter of fact, the most practical use case is by updating the cached entity without ETag associated in it.
A coder would not be able to explain this thoroughly without refreshing their minds in the industry, which is why continuous learning is encouraged.