In the Hypertext Transfer Protocol (HTTP), HTTP header fields contain the operating parameters of an HTTP request or response. With the request or response line (first line of message), they form the message header.

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10k views

difference between accept and content-type http headers

So the accept header tells the server the mime-type of the resource the browser is looking for. For example, the server can send plain text, html, json, etc. Ok that makes sense. But then I look at ...
13
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2answers
3k views

What are the Consequences for using Relative Location Headers?

According to the spec, Location headers used in a redirect require a server name HTTP/1.1 301 Moved Permanently ... Location: http://example.com/foo/baz/bar However, in 2012, most web browsers will ...
13
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1answer
249 views

What's the best way to end a Web site?

I have a Web site, built on ASP.NET MVC 3, that will be closing down completely. The domain will still be required for a few months, so during that time I'd like to display a single message on at ...
13
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1answer
4k views

What is recommended minimum object size for gzip performance benefits?

I'm working on improving page speed display times, and one of the methods is to gzip content from the webserver. Google recommends: Note that gzipping is only beneficial for larger resources. Due ...
12
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1answer
14k views

Headers to prevent 304/If-modified-since/HEAD requests

What headers should I be sending to outright stop all requests to the server after the content has been cached? We have a very high latency server (Sigh, VMWare) so even sending a HEAD request to the ...
11
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2answers
2k views

Considerations of the HTTP Content-MD5 Header

We are debating whether to use the Content-MD5 header. Pros: The CMS allows us to easily include it with minimal overhead (cached responses in 80%+ of the cases). It would add another layer of ...
10
votes
1answer
13k views

Character set not specified in HTTP headers error

When testing this page with Page Speed, I get the a Specify a character set error: The following resources have no character set specified in their HTTP headers. Specifying a character set in HTTP ...
8
votes
2answers
3k views

When to use and not to 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 ...
8
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2answers
305 views

Does the 'Server' header serve any purpose?

For example, when I dump the response header for my server I get: Server: Apache/2.2.11 (Ubuntu) PHP/5.2.6-3ubuntu4.5 with Suhosin-Patch mod_ssl/2.2.11 OpenSSL/0.9.8g Is this used for anything? Is ...
7
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1answer
230 views

Why is “29030400” seconds used as a common value for cache expiration?

I noticed that 29030400 is used very often in the Expires directives for static files. Google recommends to cache this kind of files up to 1 year (1 month at least). I did the math: 29030400 seconds ...
7
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3answers
1k views

How to tell the Browser the character encoding of a HTML website regardless of Server Content-Type Header?

I have a HTML page that correctly (the encoding of the physical on disk matches it) announces it's Content-Type: <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> ...
7
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3answers
1k views

Important fields in HTTP header from security perspective

What are the Important fields in HTTP header from security perspective? I tried to google it but unable to find. Can anybody provide me a link to read about it? Thanks in advance.
7
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2answers
201 views

What should happen when content is deleted?

I am wondering about the standard handling of deleted data links from an application and an SEO perspective. I have an application where users can create content but they can also delete content. ...
7
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1answer
134 views

Does the SPDY protocol eliminate the need for cookieless domains?

With plain HTTP, cookieless domains are an optimization to avoid unnecessarily sending cookie headers for page resources. However, the SPDY protocol compresses HTTP headers and in some cases ...
6
votes
1answer
2k views

Can I set a variable “Expires” in Amazon S3?

I have a ton of files in Amazon S3 (served via Cloudfront) for which I have added an Expires header of Mon, Jan 1 2024 11:11:11 GMT However, I have recently learned that setting an Expires header ...
5
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2answers
46 views

What headers/META headers should I be using for an infinite link system like a calendar?

I have a web calendar, all my own work. It works fine. But I see in the logs a bunch of search indexers go round and round and round trying to chase every link. It could go forward to the year 3000 ...
5
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2answers
88 views

Browser privacy improvement implications for websites

On https://panopticlick.eff.org/ EFF let you test the number of uniquely identifying bits that the browser gives a website. Among these are HTTP header fields such as User-Agent, Accept, ...
5
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1answer
3k views

HTTP Header Cache Time: s-maxage and max-age

I am setting up a CDN for my website, I found the following sample for adding to the 'httpd.conf' file, this is used to adjust the cache-time for client and CDN: ExpiresActive On ExpiresByType ...
5
votes
1answer
418 views

How do Expires headers and cache manifest rules work together?

I find the W3C's official Offline Web Applications specification to be rather vague about how the cache manifest interacts with headers such as ETag, Expires, or Pragma on cached assets. I know that ...
5
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3answers
924 views

What does it mean when a User-Agent has another User-Agent inside it?

Basically, sometimes the user-agent will have its normal user-agent displayed, then at the end it will have the "User-Agent: " tag displayed, and right after it another user-agent is shown. Sometimes, ...
4
votes
2answers
271 views

Why doesn't this web crawler obey requests to stop crawling my pages?

I have a hidden page that verifies internal payments from PayPal. The page has the following in its HTTP headers: X-Robots-Tag: noindex, nofollow But once in a while I see this in the page logs: ...
4
votes
2answers
172 views

HTTP response for deleted or disabled items on ecommerce store

What HTTP response should you send when an item/category on your ecommerce site has been disabled or deleted? 410 looks correct for deleted products but not sure about something that has been disabled ...
4
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1answer
446 views

Is it necessary to specify content-type in http response header?

Except for the html document, currently all the files (css, javascript and images) served from my web server do not specify the content-type in the http response header. I happen to notice this as I ...
4
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2answers
613 views

What's the best way to determine users' preferred language?

In determining which language to display content in by default, there are, as far as I know, three basic methods: Examine the Accept headers sent by the browser. Use IP geolocation to determine the ...
4
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1answer
207 views

HTTP Headers caching

I am not totally sure bout HTTP headers, but from what I read its good to have some level of caching on static pages also I am not sure if Transfer Encoding: chunked is a good thing. I was not finding ...
3
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2answers
2k views

Should 304 Not Modified responses include the “Last Modified” header?

I've been using the most excellent http://redbot.org tool for testing have HTTP headers on my site correct (its custom code in PHP serving dynamic content - wanting to ensure it cached where possible ...
3
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3answers
239 views

PHP Include meta tags

A website I'm currently working on is http://www.troubi.com . Please don't care to look at the source code. If I validate the website through the w3cValidator a lot of errors occur all due to ...
3
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1answer
180 views

Should we allow HEAD requests?

Our web application is predominantly read-only. As such we only allow GET requests. However, we regularly get errors in our logs because of user agents making HEAD requests. I've seen these come from ...
3
votes
1answer
1k views

What should my expires, cache-control, and pragma HTTP request header fields be set to?

I have a website in which I update the content approximately once monthly. When I check the HTTP request header fields, I get the following output: Expires: Thu, 19 Nov 1981 08:52:00 GMT ...
3
votes
1answer
518 views

Sitemap file getting double compressed

I have a script that generates my XML sitemap and writes it to the file sitemap.xml.gz - i.e. an XML file, compressed with gzip. This file is definitely written correctly as when I download it via FTP ...
3
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1answer
131 views

Can server break clients' cache settings?

I have disputed a domain name to a cybersquatter that I expect to recover soon. The problem is that the cybersquatter has changed the cache headers and now every user who already visited the site or ...
3
votes
1answer
225 views

Use - or misuse - of ETags

I'm using an application that sets ETags by md5()ing the URL. As I understand it, that's quite insane. In effect, it means that content for a specific URL won't be fetched anew ... ever. Unless a ...
2
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2answers
992 views

How do I modify the HTTP headers?

Google page speed rank demands me to set an expiry date or a maximum age in the HTTP headers, by changing the "Expires" and "Cache-Control: max-age". The site is hosted on a hosting company (not in ...
2
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2answers
98 views

Why does the website heading on pubvantage.com display arbitrary text when it is listed in google search results?

the website www.pubvantage.com has a permanent redirect to http://exchange.contextweb.com/sellingdesk/pubvantage/. The problem is, when a user enters the query +"pubvantage" in google, the site ...
2
votes
1answer
68 views

Why was 303 skipped in HTTP/1.0?

While looking back over HTTP response codes today I noticed that the 301, 302, and 304 response codes were defined in HTTP/1.0 but not the 303 response code. Does anyone know why the number 303 was ...
2
votes
1answer
254 views

Can I set Cache-Control in the .htaccess file for a specific part of a document (just a section of the <body>)

I noticed, by using Google Page Speed Insights, that if I structure my HTML to load the critical, above-the-fold content first, my page will improve performance - and it woks (with now current perf. ...
2
votes
1answer
135 views

What's the best HTTP code for dynamically deleted pages?

I've built my own CMS and I'm looking for the best way to handle pages / items deletion. Actually, pages and items were deleted and cannot be restored. But since I have implemented a bin, I don't ...
2
votes
1answer
2k views

Google Chrome audit: resources are explicitly non-cacheable?

If I run a Google Chrome audit on a site, it lists all CSS, PNG, JPG, JS files and even the main domain (i.e. www.example.com) under the heading: Leverage browser caching The following resources ...
2
votes
1answer
94 views

How to configure apache2 to just save certain POST requests without even passing them to application?

I'm running Apache in front of glassfish server using BalancerMember. For performance reasons I would like that POST requests on certain endpoint are just saved to a file without passing them to ...
2
votes
2answers
286 views

Using Pragma header on HTTP 1.1

would like know your opinion about using Pragma header when script is called in HTTP version 1.1 I don't know is good to return both Pragma and Cache-Control or rather return only Cache-Control ...
2
votes
1answer
122 views

Caching preventing users seeing site updates

I'm experiencing a caching issue I can't explain. This is happening across browsers, IPs and ISPs. If a user force-refreshes, they see the new content. If they then refresh or return to the page, the ...
2
votes
1answer
497 views

Problem with Expires/Cache-Control Headers

I'm using Apache 2.2.16. I've got the following HTML file in my htdocs folder: <html> <link media="screen" type="text/css" href="/css/test.css" rel="stylesheet" /> ...
2
votes
2answers
82 views

Verifying that a user comes from a 'partner' site?

We're building a Drupal module that is going to be given to trusted 'corporate partners'. When a user clicks on a link, he should be redirected to our site as if he's a logged in user. How should I ...
1
vote
2answers
390 views

Temporary website redirect: 3xx or php/meta?

I run a (small) news website which has also a forum in a subfolder of the root. I'm planning to give the site a facelift and a code restructuration, so I wanted to put some redirect on the home page ...
1
vote
2answers
320 views

“Cannot modify header information” error in my PHP/WordPress site

I edited the header.php and functions.php files in my WordPress site to add Google Analytics tracking code. Now, when I try to login to my admin area, the following warning appears and I am unable to ...
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2answers
1k views

Lots of HTTP HEAD requests originating from porn sites

The access log on my web server has a ton of HTTP HEAD requests coming from porn sites. What are HEAD requests and are they doing something bad with my site? Here is an excerpt from my log: (valid ...
1
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1answer
2k views

IP Address headers (Remote_Addr) - When is this header sent by the browser?

I want to know when a browser includes the header - Remote_Addr in the HTTP request. I observed the request sent by the browser on loading stackoverflow.com, in the web console window of Firefox. ...
1
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2answers
1k views

Is no cache meta tag bad for performance?

I see many websites, seemingly arbitrarily adding the no cache meta tag on every page. Like this: <META HTTP-EQUIV="PRAGMA" CONTENT="NO-CACHE"> <META HTTP-EQUIV="CACHE-CONTROL" ...
1
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1answer
767 views

Enforcing a specific order for cookie headers

We have an application that cares about the order of cookie headers. It shouldn't, since this isn't mandated by the standards and indeed we're getting the headers in various different orders So we ...
1
vote
1answer
49 views

Did I use the proper way to remove pages from Google Webmaster Tools forever?

I have many pages from one year ago that were deleted and are returning a 404 error code, but two week ago after I cleared the content of my robots.txt, the errors in my Google Webmaster Tools reports ...