WCF Service Access denied

Dear All,

We have developed a WCF service and hosted in IIS in one machine, and we are consuming this WCF

service in a web application which is hosted in another machine, both WCF and web application

machines are in same domain. And we are invoking the WCF service in javascript.

If I run the web application using localhost or domain name or IP address ex.

able to invoke the the WCF service without any problem. But when I run the web application using

FQDN(Fully Qualified Domain Name) i.e. http://mysystemname.cp.sub.com/mywebapp Iam not able to

invoke the WCF service, Iam getting 'Access denied' error.

I did below things to resolve the issue but no luck.

1. Entered the IP address and FQDN(Fully Qualified Domain Name) in host file where web

application exists.

2. Given full permissions to IIS_IUSRS where WCF service exists.

Could you please suggest me what else I need to do to resolve this issue.

Thanks,

Udayv