Configure Domain And Subdomain On Tomcat

I have configured Apache+Tomcat on Linux server. I have configured 50+ domains not problem is that sometime when i configure new domain and restart the service and access the url http://domain.com i get following error ----->

HTTP Status 404 - /

type Status report

message /

description The requested resource (/) is not available.

but when i access same url with file like [url]i able to access that url and working fine.
same problem for subdomain also [url]same error but [url]is working so can anyone tell me what is the exact problem and how to solve this problem.

Note:- Other domains are working fine this problem is only with 2-3 domains and subdomain and secondly i have also set DirectoryIndex index.html index.jsp index.php

Please check my server.xml and httpd.conf ------->

<Host name="domain.com" appBase="/home/domain/public_html">
<Alias>www.domain.com</Alias>
<Context path="" reloadable="true" docBase="/home/domain/public_html" debug="1"/>
<Context path="/manager" debug="0" privileged="true"
docBase="/usr/local/jakarta/tomcat/server/webapps/manager">
</Context>
</Host>

<VirtualHost 192.168.1.1:80>
ServerName domain.com
ServerAlias www.domain.com
DocumentRoot /home/domain/public_html
ServerAdmin webmaster@domain.com

JkMount /*.jsp ajp12
JkMount /*.jsp ajp13

</VirtualHost>