keep-alive Validation SEO Tool

How do you check if your website is using Persistent Connection?

You can easily check if your website supports Persistent Connection by following these steps:

• Enter your website in the above URL field (If you have to check multiple URLs switch to the Bulk mode).

• Click on the Check button.

• We will analyse your web server and let you know if it uses a Persistent Connection.

• If not, we will tell you how to enable it on your web server.

• We will also check if there are external server calls and give you the option to bulk check the Persistent Connection status of those servers.

Keep-alive is the value of the Connection header that is used to indicate that the server supports persistent connection.

In the world of SEO, when you hear that the server does not support HTTP persistent connection or HTTP keep-alive it usually means the same thing. Some people might also call it HTTP connection reuse.

The default HTTP 1.0 connection is usually closed after each request has been completed, meaning that the server closes the TCP connection after delivering the response. In order to keep the connection open for multiple requests, the keep-alive connection header can be used. In HTTP 1.1 connection is open by default unless the server or client explicitly sets it to close. In HTTP 2 connection is always open. The Connection: close header is ignored on HTTP 2.0

Here is a table outlining if the client server connection is a persistent connection.

Enabling Connection: keep-alive through the httpd.conf file is the preferred method for Apache servers, but if you are on shared hosting you probably wouldn't have access to the httpd.conf file. Instead, try enabling Persistent Connection using the .htaccess file.

Follow these steps to enable Persistent Connection:

• FTP into your server and look for the .htaccess file in the root folder of your web server.

• Take a backup of that htaccess file.

• Open the htaccess file in a text editor and add the following code ( if you are running a WordPress site look for “# END WordPress” and add this code after that )

  <IfModule mod_headers.c> 
      Header set Connection keep-alive
  </IfModule>

• Upload the new .htaccess file and overwrite the old one.

• Wait for a while and recheck if Persistent Connection is enabled using this tool.

In most cases Keep-alive should be enabled automatically if you are using HTTP 1.1 or above. To enable Connection: Keep-Alive all you have to do is edit your Apache config file. It is usually found at /etc/httpd/conf/httpd.conf

There are three settings you can modify here:

• KeepAlive: Set it to "KeepAlive on" to enable keep-alive.

• MaxKeepAliveRequests: Sets the maximum number of requests to allow during a persistent connection. Set it to "MaxKeepAliveRequests 60"

• KeepAliveTimeout: Sets how long your server should wait for new requests from clients. Set it to "KeepAliveTimeout 3"

NOTE: Web server will usually have a concurrency limit or scalability problem, and when they hit that limit, performance will drop. Keep in mind there are no one-size-fits-all numbers for MaxKeepAliveRequests and KeepAliveTimeout, so speak to you hosting provider OR Webmaster to see what numbers work best for you.

On NGINX Servers Persistent Connection is usually enabled for most modern browsers but it can be disabled for older browsers using the keepalive_disable directive in ngx_http_core_module. If the value is set to msie6, we would advise to leave it as it is BUT if for some reason it’s set to be disabled for modern browsers too, have a word with your host / Webmaster to find out why and possibly get it removed. The value none enables keep-alive connections with all browsers.

Persistent Connection is enabled by default for LiteSpeed Servers, there is no “yes/no” or “on/off” option its server settings. But you can go into LSWS Admin Console → Server → Tuning → Connection section to modify the Max Keep-Alive Requests, Smart Keep-Alive, and Keep-Alive Timeout (secs) settings.

NOTE: Smart Keep-Alive is a feature in LiteSpeed Servers that is useful for high volume websites where Persistent Connection is disabled for HTML files but other assets like CSS, JS, images, etc. will have Persistent Connection enabled. If you don't have a high volume site you could disable the Smart Keep-Alive feature.

If you are running a Microsoft IIS Server, you can enable Persistent Connection by:

• Going into IIS Manager.

• In Features View, double-click HTTP Response Header

• In the Actions pane, click Set Common Headers

• In the Set Common HTTP Response Headers dialog box, select the Enable HTTP keep-alive, check box and then click OK

Check out this page for more info.