Apache delivering wrong SSL-Cert - apache

Question

I have a Server which is running Debian 8.1 with Apache 2.4.10 and OpenSSL 1.0.1k.
I have a domain example.com with a few subdomains like www.example.com, cloud.example.com and db.example.com all pointet to the Server (A-Records).
All these subdomains have their own VirtualHosts with their own SSL-Certificates. Also if you send a HTTPS-Request with another domain or with the IP you'll get a page with a self-signed certificate.
Everything was running perfect until I rebootet my server.
Now when I request example.com (without a subdomain-prefix) I get the self-signed crt. The subdomains are working perfectly fine. I have the following vHost-Configs:
(because I only want HTTPS I have a Rewrite-Rule for all HTTP-Connections)
000-default.conf
<VirtualHost *:80>
ServerAdmin admin#example.com
RewriteEngine On
RewriteRule ^/?(.*) https://%{SERVER_NAME}/$1 [R,L]
ErrorLog ${APACHE_LOG_DIR}/error.log
# Possible values include: debug, info, notice, warn, error, crit, alert, emerg.
LogLevel warn
CustomLog ${APACHE_LOG_DIR}/access.log combined
</VirtualHost>
<IfModule mod_ssl.c>
<VirtualHost *:443>
ServerAdmin admin#example.com
DocumentRoot /var/www
<Directory /var/www>
AllowOverride All
Require all granted
</Directory>
Header always set Strict-Transport-Security "max-age=31536000; includeSubDomains"
ErrorLog ${APACHE_LOG_DIR}/error.ssl.log
LogLevel warn
CustomLog ${APACHE_LOG_DIR}/access.ssl.log combined
SSLEngine on
SSLCertificateFile /etc/ssl/certs/default/ca.crt
SSLCertificateKeyFile /etc/ssl/certs/default/ca.key
</VirtualHost>
</IfModule>
www.example.com.conf
<IfModule mod_ssl.c>
<VirtualHost *:443>
ServerAdmin admin#example.com
ServerName www.example.com
ServerAlias example.com
DocumentRoot /var/www/example
<Directory /var/www/example>
AllowOverride All
Require all granted
</Directory>
Header always set Strict-Transport-Security "max-age=31536000; includeSubDomains"
ErrorLog ${APACHE_LOG_DIR}/error.ssl.log
LogLevel warn
CustomLog ${APACHE_LOG_DIR}/access.ssl.log combined
SSLEngine on
SSLCertificateFile /etc/ssl/certs/www.example.com/ca.crt
SSLCertificateKeyFile /etc/ssl/certs/www.example.com/ca.key
SSLCertificateChainFile /etc/ssl/certs/www.example.com/sub.class1.server.ca.pem
SSLCACertificateFile /etc/ssl/certs/www.example.com/ca.pem
</VirtualHost>
</IfModule>
cloud.example.com.conf
<IfModule mod_ssl.c>
<VirtualHost *:443>
ServerAdmin admin#example.com
ServerName cloud.example.com
DocumentRoot /var/www/example
<Directory /var/www/example>
AllowOverride All
Require all granted
</Directory>
Header always set Strict-Transport-Security "max-age=31536000; includeSubDomains"
ErrorLog ${APACHE_LOG_DIR}/error.ssl.log
LogLevel warn
CustomLog ${APACHE_LOG_DIR}/access.ssl.log combined
SSLEngine on
SSLCertificateFile /etc/ssl/certs/www.example.com/ca.crt
SSLCertificateKeyFile /etc/ssl/certs/www.example.com/ca.key
SSLCertificateChainFile /etc/ssl/certs/www.example.com/sub.class1.server.ca.pem
SSLCACertificateFile /etc/ssl/certs/www.example.com/ca.pem
</VirtualHost>
</IfModule>
I really hope that somebody can help me!

Answer 1

The hostname was example (like the domain, but without .com) so I changed the hostname to some random typing and after a reboot everything worked fine again. When I changed my hostname back it kept working even after a reboot.

Answer 2

For me changing the order of VirtualHosts helped to solve the problem, by putting malfunctioning VirtualHost to the top in the conf file.