As explained several times, you were asking multiple generalized questions about how CDNs work. Here are the questions you asked, copied verbatim from your question:
How do CDNs' caches handle 'Vary: User-Agent' headers?
Am I correct that with the current configuration proxies/caches won't
care about user-agent and will serve whatever they have cached?
However, the negative side-effect of that is that these
proxies/caches/CDNs will have to keep separate copies for every single
unique user-agent+gzip combination they encounter...and that could be
This translates into a lower cache hit ratio, potentially higher load
on the origin server and potentially less optimal end user experience.
How do various CDNs handle this situation?
Do they truly keep copies for every single combination or do they
combine user agents into larger buckets, ie
Firefoxes/Chromes/IEs/Operas/Safaris or do they outright ignore this
header or is there something in between?
As also explained several times, questions here need to be about a website under your control, not about how all CDNs might work, and suggested that if you edit your question to ask one specific question about one particular CDN in relationship to your site, it would be reviewed by others and possibly be reopened.
Here is my first comment in this regards:
As it stands, this question is asking several generalized questions in
regards to CDNs. Please narrow this down to one specific question,
about one particular CDN in relationship to your website.
Despite the above, you edited the question to just add bold to one of your questions, and commented back:
@dan this question is asking a single specific question: how CDNs
Vary: User-Agent header. This question is long because I put
in detailed explanation of the situation in which this applies to
and for people to understand this issue at hand.
Your question was reviewed again by others and voted to leave it closed.
I also commented back:
You may have added bold to one question, but you're asking several
others too. Questions here need to be about a site under your control,
not about how all CDNs might work. If you narrow it down to just one
question about a particular CDN in relationship to your site, it might
You then made another very minor edit, without narrowing down the questions or making it specific to one CDN in relationship to your site.
Again your question was reviewed and voted to leave closed.
You then flagged the question for moderation, complaining that others had voted to close it unfairly, which was declined by another moderator.
Then you left two quite obviously angry comments back-to-back, copied verbatim:
@dan What multiple questions am I asking?! There's only 1, very clear
question that I asked in the title and in the body. Does knowing how
CDNs handle Vary header is not covered by a scope of knowledge of
webmasters in general and this site specifically?!
@dan there! I removed what could possibly be considered
"other questions". Now my question has just a single clear question
and there's no reason for it to be flagged for closure.
I then left a comment explaining why it was being deleted after all of that:
You're still asking multiple questions (count your question marks)
about how all CDNs work, instead of one specific question about a
particular CDN in relationship to your site. This was voted closed
multiple times, so it's being deleted since you don't seem to be
I suggest you refer to the following Help FAQ: Why and how are some questions deleted? As stated there:
Questions that are extremely off topic, or of very low quality, may be
removed at the discretion of the community and moderators. Over time,
closed questions that are not useful as signpoints to other questions
may also be removed, as well as questions which have no significant
activity over a very long period after being asked. If you want to
improve a question to keep it from being deleted, click the edit
button beneath it.
Questions can also be deleted by the community. Moderators can delete
any question, and users with sufficient reputation can cast delete
votes on closed questions. It takes 3 votes, minimum, to delete a
closed question. However, the number of delete votes required scales
to the number of votes on the question and all its answers. Questions
that have been closed within the past 48 hours cannot be deleted, so
as to allow for editing and possible reopening.
Additionally, any answer that accumulates enough offensive or spam
flags will be automatically deleted.