How have WLANs changed ‘hard edges' into ‘blurred edges'?

What will be an ideal response?

The introduction of wireless LANs in enterprises has changed hard edges to blurred edges. Instead of a network hard edge with a single data entry point and solid walls to protect physical access to the wired LAN, a WLAN can contain multiple entry points.  In
addition, because RF signals extend beyond the boundaries of the building the walls cannot
be considered as a physical hard edge to keep away attackers.