We have Servlet 2.3 deployment descriptor (web.xml), which follows J2EE 1.3 DTDs schema.
Therefore it requires dtd resource hosted at http://java.sun.com/dtd/web-app_2_3.dtd
In setups that are behind firewalls with limited access to external resources, the Atlas server fails to come up without the external dtd resource.
This can be fixed by hosting dtd resource locally or upgrading the deployment descriptor.
We can upgrade it to Servlet 2.5 deployment descriptor which is Java EE 5 XML schema and it does not require external dtd resource for validation.