Apache serving name-based virtual Host from server hostname (but shouldn't be) - apache

Question

I have an Apache httpd server (2.4.6) running on Centos, serving several Name-based virtual hosts. The fqdn / hostname of the server should be serving no content, but it redirects to one of the Name-based virtual hosts and I don't understand why, or how to stop it.
In the configs below, a request to http://host.mydomain.org/ is redirected to http://www.customer.co.uk/.
Any ideas as to why, and the right way to stop it appretiated.
My httpd.conf is:
ServerRoot "/etc/httpd"
Listen 80
Include conf.modules.d/*.conf
User apache
Group apache
ServerAdmin root#xxx.org
ServerName host.mydomain.org:80
<Directory />
AllowOverride none
Require all denied
</Directory>
DocumentRoot "/var/www/html"
<Directory "/var/www">
AllowOverride None
Require all denied
</Directory>
<Directory "/var/www/html">
Options None
AllowOverride None
Require all denied
</Directory>
<IfModule dir_module>
DirectoryIndex index.html
</IfModule>
<Files ".ht*">
Require all denied
</Files>
ErrorLog "logs/error_log"
LogLevel warn
<IfModule log_config_module>
LogFormat "%h %l %u %t \"%r\" %>s %b \"%{Referer}i\" \"%{User-Agent}i\"" combined
LogFormat "%h %l %u %t \"%r\" %>s %b" common
<IfModule logio_module>
# You need to enable mod_logio.c to use %I and %O
LogFormat "%h %l %u %t \"%r\" %>s %b \"%{Referer}i\" \"%{User-Agent}i\" %I %O" combinedio
</IfModule>
CustomLog "logs/access_log" combined
</IfModule>
<IfModule alias_module>
ScriptAlias /cgi-bin/ "/var/www/cgi-bin/"
</IfModule>
<Directory "/var/www/cgi-bin">
AllowOverride None
Options None
Require all denied
</Directory>
<IfModule mime_module>
TypesConfig /etc/mime.types
AddType application/x-compress .Z
AddType application/x-gzip .gz .tgz
AddHandler cgi-script .cgi
AddHandler cgi-script .pl
AddType text/html .shtml
AddOutputFilter INCLUDES .shtml
</IfModule>
AddDefaultCharset ISO-8859-1
<IfModule mime_magic_module>
MIMEMagicFile conf/magic
</IfModule>
EnableSendfile on
TraceEnable Off
ServerTokens Prod
IncludeOptional conf.d/*.conf
An example virtual host is:
<VirtualHost *:80>
DocumentRoot /home/xxx/customer/docs
ServerName www.customer.co.uk
ErrorLog /home/xxx/customer/logs/error_log
CustomLog /home/xxx/customer/logs/access_log combined
<Directory /home/xxx/customer/docs>
AllowOverride None
Options None
Require all granted
</Directory>
</VirtualHost>
<VirtualHost *:80>
ServerName customer.co.uk
Redirect permanent / http://www.customer.co.uk/
</VirtualHost>
<VirtualHost *:80>
ServerName www.customer.mydomain.org
Redirect permanent / http://www.customer.co.uk/
</VirtualHost>
Thanks very much
Kevin

Answer 1

The first VirtualHost in the configuration file has the highest priority and can be seen as the default or primary server. That means that if a request is received that does not match one of the specified ServerName or ServerAlias directives, it will be served by this first <VirtualHost>.
You can prevent this by adding this (for example) as the first VirtualHost:
<VirtualHost *:80>
ServerName default
RewriteEngine On
RewriteRule ^ - [F]
</VirtualHost>