What is the function of Priority Delta in VRRP?

Priority Delta in the context of the Virtual Router Redundancy Protocol (VRRP) plays a crucial role in determining the effective priority of a VRRP router when certain conditions in the network change. Specifically, when a box (or router) is operational and participating in the VRRP configuration, Priority Delta adds additional value to the base priority of the router.

This means that when the router is active and handling traffic, its Effective Priority is calculated by adding the Priority Delta to its configured Priority. This adjustment helps establish the router's standing in the group of VRRP routers, allowing it to maintain a higher chance of being selected as the Master router. The concept of Effective Priority is vital as it informs the election process during various scenarios, ensuring that the most suitable router remains in control.

When a router is functioning properly, enhancing its priority through the addition of Priority Delta reinforces its capability to manage network traffic effectively, especially in environments that require high availability and resilience.

The other options incorrectly relate the scenarios of box failure or interface status without accurately tying them back to the intended effect on the Effective Priority during normal operation. In short, the correct understanding of Priority Delta ensures that routers are optimally configured to maintain network reliability when they are up and running.