Thanks...this is the useful link for error 404.3 and 500.21 internal server
For 404.3 - http://stackoverflow.com/questions/16458059/http-error-404-3-in-iis
and
for 500.21 - http://www.winsysadminblog.com/2011/08/fixing-http-error-500-21-internal-server-error-handler-webservicehandlerfactory-integrated-has-a-bad-module-managedpipelinehandler-in-its-module-list-on-iis/