Questions tagged [etags]

Entity tags (ETags) are a mechanism that web servers and browsers use to determine whether the component in the browser's cache matches the one on the origin server.

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1 answer
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ETag-based content revalidation

My CMS generates pretty complex pages and thus takes a little while to do so (about 2 seconds), which is well above my time budget to serve pages to the client. However it's very cheap for me to know ...
2 votes
1 answer
5k views

Which static file types does Nginx generate ETags for by default?

In modern versions of Nginx, the ETag is automatically generated for static file types, even if you don't specifically enable the etag on in your location blocks or otherwise: https://nginx.org/en/...
0 votes
0 answers
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How to disable ETag headers in Tomcat 9?

How to disable ETag headers in Tomcat 9 ? It will be helpful if provided with details/examples etc. Need to remove etags as this is reported as vulnerability in security scan . Tried different ...
0 votes
0 answers
144 views

Do ETags generated on upstream need If-None-Match check? (NGINX)

(Reposting my post deleted after a year of inactivity) Let's assume I use etag off (and if_modified_since off with add_header Last-Modified "" to not make redundancy) in NGINX and I generate ...
5 votes
3 answers
4k views

What are the benefits and drawbacks of using ETag vs LastModified as a CDN cache validator?

I'm reading this article on Azure CDN. I can either control caching with: An ETag Last Modified Default heuristics What are the benefits and drawbacks of the first two choices? Does it matter? ...
0 votes
1 answer
1k views

How to generate ETag for HTML (full page) content in Varnish?

I want to configure Varnish to generate ETag of HTML requested content (maybe with MD5 of HTML and "Vary" headers) and to deal with 304 and If-None-Match headers. Is this possible with ...
5 votes
0 answers
1k views

Client-side caching when using CSP with nonces in nginx - how do you use weak caching validators/etags?

I'm using nginx's expires directive; its etag directive as well as the Last-Modified header (if I understand correctly) are on by default. In order to allow specific inline JavaScripts when using ...
4 votes
1 answer
2k views

How do Proxies handle ETags?

I use ETags to improve performance. I decided to use an Etag that is valid on Server, Client and Proxy. But how is this handled if the proxy has saved the ETag? Does the Proxy still ask the website ...
6 votes
1 answer
8k views

Nginx sending 2 Cache-Control headers

Iam serving my static content with ngnix. location /static { alias /opt/static/blog/; access_log off; etags on; etag_hash on; etag_hash_method md5; expires 1d; ...
1 vote
1 answer
321 views

Can Squid automatically add ETag? [closed]

Can Squid automatically add ETag based on page content, for the client not to download the same page twice?
0 votes
0 answers
2k views

How to configure entity tags (ETags) on IIS 8.5?

YSlow is complaining about some images with misconfigured ETags, I found some articles and followed the instructions, but it is still not working for me in IIS 8.5 Any idea what is the right way to ...
10 votes
1 answer
4k views

When should you use and not use Etags?

I was just looking at our site on WebPageTest.org and one of their recommendations for speeding up a website is: ETag headers should generally not be used unless you have an explicit reason to need ...
1 vote
2 answers
1k views

Apache Caching and Expires configuration

I'm looking for a best possible caching/expires configuration for my specific situation. I realize that some sites have advocated turning etags off: Header unset ETag, FileETag None I know that I ...
8 votes
5 answers
8k views

Which reverse-proxies support HTTP/1.1 ETag and If-None-Match headers?

I'm developing a caching system for an ecommerce platform that will use a reverse proxy for caching. I plan to handle invalidation by using proper HTTP/1.1 headers. That is, I will set an ETag on ...
6 votes
1 answer
527 views

RFC 2616 with Apache 2.4

I'm using Apache 2.4.3 as a reverse proxy due to it's advertised compliance with RFC 2616. My app uses headers like this to enable caching at the proxy: Cache-Control: public, s-maxage=0 Expires: ... ...
20 votes
7 answers
38k views

yslow says etags are misconfigured. how to configure etags properly on IIS7?

running ySlow on a website I support, I noticed it reported that the etags are misconfigured for the site images (e.g. *.jpg, *.png, *.gif). Can anyone help explain what I have to do to get IIS7 ...
2 votes
1 answer
305 views

What strategy should I use for Apache HTTP Server so that newly deployed files have their cache invalidated?

A very common solution is to do the following: <ifModule mod_headers.c> FileETag None Header unset ETag Header set Cache-Control "max-age=0, no-cache, no-store, must-revalidate" ...
0 votes
2 answers
260 views

Prompt server for Etag or MD5

We are a price comparison portal and crawl certain websites on a regular basis. I am looking for a method to save bandwidth by avoiding downloading the same page over and over again if the content did ...
1 vote
2 answers
5k views

Apache Etags, need help?

We do not currently use Expire headers, I was going to recommend it but forcing our large development team/business to change their practices and rename static files with each new release isn't going ...
5 votes
1 answer
13k views

How to disable ETag headers in Tomcat

Tomcat seems to send an ETag header with each response by default. I'd like to disable these for reasons outlined here. I know I can strip them out in my Apache configuration, but is there any way to ...
2 votes
2 answers
1k views

disable etag in IIS 7

Does anyone know how I can disable ETag on IIS 7?
1 vote
1 answer
3k views

What is Apache's purpose in putting inodes into ETags?

There are plenty of articles on the web detailing why you might not want to use Apache's default inode-mtime-size format for ETags (see e.g. here or here). All such articles recommend the same thing: ...