For port-based tunneled node configurations, VLANs assigned to support tunneled-node endpoints typically do not have an IP address configured. This is because the VLAN is used to handle traffic that is tunneled to an Aruba controller, which means the IP addressing is managed by the controller, not the switch itself. Hence, VLAN 20 should not have an IP address.

When there is a range mismatch between two ABRs in OSPF, they can lose adjacency within the area where the mismatch occurs. As a result, the ABRs must route all traffic to each other through the backbone area, which is Area 0 in OSPF. This situation does not create a discontinuous area or disrupted intra-area routing but rather forces traffic to follow a less efficient path, impacting overall routing efficiency.

To minimize congestion on Link 1, switch-to-switch traffic should be evenly distributed across the switches. By assigning Switch 2 as the root for VLANs 4 and 6, and Switch 3 as the root for VLANs 5 and 7 (as detailed in Option B), traffic will be better balanced. This ensures that no single link is disproportionately utilized, thereby minimizing congestion on Link 1.

To ensure DHCP snooping operates correctly and clients receive the appropriate DHCP settings, you need to define the trunk port (trk1) as a trusted DHCP port. By default, all ports, including trunk ports, are considered untrusted, which means DHCP offers and acknowledgments cannot pass through them. Defining the trunk port as trusted allows the legitimate DHCP traffic to be forwarded to the clients.

When Device 1 crosses the threshold and triggers the action, the switch temporarily drops all IP traffic from Device 1 only. This is in line with how connection rate filtering typically functions, where the specific offending device is targeted rather than an entire interface.