I have configured tomcat server with apache (httpd), When open my application on browser with www (www.domain.com) shows 404 error,

You need to check the CNAME record in DNS settings or host side
 

www     14400   IN      CNAME   domain.com.

The entries are correct and its working perfect need to check in server.xml file and add Alias for that domain.
 
<Host name="domain.com" appBase="/usr/local/apache-tomcat-7x/webapps/"
autoDeploy="true" xmlValidation="false" xmlNamespaceAware="false">
<Context  path=""   docBase="/usr/local/apache-tomcat-7x/webapps/test"  swallowOutput="true" crossContext="true"></Context>
</Host>

After changes,
 
<Host name="domain.com" appBase="/usr/local/apache-tomcat-7x/webapps/"
unpackWARs="true" autoDeploy="true" xmlValidation="false" xmlNamespaceAware="false">

<Alias>www.domain.com</Alias>

<Context  path=""   docBase="/usr/local/apache-tomcat-7x/webapps/test"  swallowOutput="true" crossContext="true"></Context>
</Host>

Now, restart tomcat server and check the domain with www.