My virtual hosts file for my subdomain is not being picked up

Question

So I have a website running on a lamp stack on Ubuntu.

I have two vhosts files...

000-default.conf:

<VirtualHost *:80>
    ServerName www.example.co.uk
        ServerAdmin [email protected]
        DocumentRoot /var/www/html/

        ErrorLog ${APACHE_LOG_DIR}/site-a_error.log
        CustomLog ${APACHE_LOG_DIR}/site-a_access.log combined
</VirtualHost>

And moodle.example.co.uk.conf:

<VirtualHost *:80>
    ServerName moodle.example.co.uk
        ServerAdmin [email protected]
        DocumentRoot /var/www/moodle.example.co.uk/public_html

        ErrorLog ${APACHE_LOG_DIR}/site-b_error.log
        CustomLog ${APACHE_LOG_DIR}/site-b_access.log combined
</VirtualHost>

If I go to www.example.co.uk then I see the home page. Exactly as expected.

However if I go to moodle.example.co.uk I still see the homepage not the page stored in the DocumentRoot specified.

If I add a ServerAlias directive to the Moodle conf then it works fine.

Why does the ServerName directive not work?

EDIT: an update. If i disable ALL virtual hosts then my website is still served. this seems like very odd behaviour.

The access is logged in other_vhosts_access.log but I cannot find anything that should lead to this behaviour.

With no vhosts defined should the site just give a connection refused error?

Answer 1

From Apache 2.4 documentation (may help):

When a request arrives, the server will find the best (most specific) matching argument based on the IP address and port used by the request. If there is more than one virtual host containing this best-match address and port combination, Apache will further compare the ServerName and ServerAlias directives to the server name present in the request.

If you omit the ServerName directive from any name-based virtual host, the server will default to a fully qualified domain name (FQDN) derived from the system hostname. This implicitly set server name can lead to counter-intuitive virtual host matching and is discouraged.

The following is most interesting: "If you omit the ServerName directive from any name-based virtual host, the server will default to a fully qualified domain name (FQDN) derived from the system hostname"