Access to the BIG-IP Configuration Utility (TMUI) is controlled through the /sys httpd allow list.

This list defines which IP addresses or subnets are allowed to connect to the management web interface.

To allow two new subnets— 172.28.31.0/24 and 172.28.65.0/24 —the administrator must add both subnets to the existing list without removing current entries.

In tmsh, subnet entries must be specified in network/netmask format , for example:

172.28.31.0/255.255.255.0

The correct tmsh command to append these networks is:

modify /sys httpd allow add { 172.28.31.0/255.255.255.0 172.28.65.0/255.255.255.0 }

Why the other options are incorrect:

Option B:

IPs are listed without masks, which is invalid for subnet-based access control.

The system requires network/netmask format.

Option C:

The command uses permit instead of allow, which is not a valid attribute of /sys httpd.

The correct keyword must be allow .

Thus, only Option A correctly adds both permitted subnets in the proper tmsh format.