You are designing a large-scale DMVPN network with more than 500 spokes using EIGRP as the IGP protocol. Which design option eliminates potential tunnel down events on the spoke routers due to the hol

The spoke tunnel interface hold queue governs buffering on the spoke's inbound side; the bottleneck is the hub's inability to drain hellos fast enough to all spokes, not the spokes' ability to receive them.

The spoke's physical interface queue affects traffic arriving from the WAN but is not involved in queuing the EIGRP hellos that the hub generates and sends toward spoke tunnel endpoints.

The hub's physical interface queue processes traffic after it leaves the tunnel interface; EIGRP hellos to spokes are queued and dropped at the tunnel interface before they ever reach the physical interface queue.

The hub's mGRE tunnel interface is a single logical interface that must unicast EIGRP hello packets to all 500+ spoke neighbors concurrently. Under sustained load, the default output hold queue on this interface fills up and discards hellos before they can be transmitted, causing spokes to exceed their EIGRP hold time and tear down the neighbor adjacency. Increasing the hold queue depth on the hub's tunnel interface allows more packets to be buffered before being discarded, preventing hello drops and eliminating the holding-time expiration events observed on spoke routers.

QoS pak_priority class prioritizes control-plane packets during congestion but does not expand the hold queue depth that is exhausted when the hub unicasts hellos to hundreds of spoke tunnel addresses simultaneously.