Your PXE Server has multiple NICs and you'd like to control specifically which NIC is used by PXE? You may have a different application running that also uses TFTP and you don't want the two to conflict.
By default a PXE Server will bind to whatever IP Address was specified during the installation of the Ghost Solution Suite. If it is necessary to change this, if can be done within the PXE Configuration Utility. Here's how.
What you're doing with this change is telling the PXE Server to listen on only the IP address/NIC that you want. That way it won't conflict with other applications.