Running Nessus 1.2.5
Running Nmap v3.0
Scanning FW-1 Server
On RH Linux 7.2.

Here's the question. When I run a Nessus scan on ports 1-1024, its comes back as a dead host. Using TCP scan as well. Great! Makes me happy to see that.

I also run an nmap on the same ports, using TCP scan. It returns right away with:
"Host x.x.x.x appear to be up...good"
"All scanned ports are: filtered"

Why would Nessus see the host as dead, when nmap see's the host is up. How do these two differ when it comes to verifying the server is up or down?

Big confusion for me is that Nessus has nmap in it....

Any ideas?