300-420 Exam Dumps and Practice Questions

For in-band management over the production WAN, the proper marking is DSCP CS2 mapped into the management or operations class with a minimum bandwidth guarantee. Cisco enterprise QoS guidance separates network control traffic from network management traffic. Routing protocol and control-plane traffic should not be diluted by ordinary management flows. CS6 is typically reserved for routing and network-control traffic; EF is reserved for low-latency voice bearer traffic; CS1 is commonly used for scavenger or low-priority traffic. Network management flows such as SSH, SNMP, NTP, FTP-based maintenance, and syslog require reliable delivery, but they should not starve business traffic or real-time services. Therefore, marking with CS2 and mapping the traffic into Class2 is the correct design choice. The bandwidth adjustment should come from a lower-priority class, not from the routing/control or real-time class. Because this is in-band management, the architect must also ensure access control, source restrictions, AAA, logging, and management-plane protection. QoS classification alone does not secure management access; it only gives the traffic an appropriate forwarding treatment over the MPLS WAN. Reference topics: in-band management, DSCP CS2, enterprise QoS classes, management-plane traffic.

Traffic shaping is required in the parent policy when hierarchical QoS uses CBWFQ in the child policy for low-bandwidth remote sites. In Cisco hierarchical QoS, the parent policy commonly shapes outbound traffic to the real available rate of the WAN service, especially when the physical interface speed is higher than the provider committed rate. The child policy then applies class-based queuing, such as CBWFQ and LLQ, inside the shaped rate. This structure creates an artificial congestion point on the router so the child queues can schedule packets predictably instead of allowing the provider to drop traffic after it exceeds the service rate. Policing in the child policy would drop excess packets and is not the normal prerequisite for nested CBWFQ. CBWFQ is supported in child policies within hierarchical designs, and parent shaping is the mechanism that makes the hierarchy effective. This is especially important on low-bandwidth WAN links where voice, video, and business-critical applications require deterministic treatment. Reference topics: hierarchical QoS, CBWFQ, parent shaping, child queuing, WAN QoS design.

The Cisco SD-Access edge node acts as the access-layer fabric device that connects endpoints to the fabric, provides the anycast Layer 3 gateway, and maps users or endpoints into the correct virtual network. Cisco SD-Access fabric edges register endpoint information with the control-plane node and encapsulate user traffic into VXLAN for transport across the fabric. The anycast gateway function allows a consistent default gateway to exist on multiple edge nodes, supporting mobility without forcing traffic through a central gateway. The edge node also applies policy context by associating users, endpoints, or ports with a virtual network and scalable group information. Advertising EID subnets is primarily associated with border connectivity and external route advertisement. LISP proxy tunnel router functionality belongs to border node behavior for external connectivity. Routing and transporting IP packets between fabric nodes is the intermediate-node underlay role. Therefore, the two edge-node functions in the options are acting as the anycast Layer 3 gateway and mapping users to virtual networks. Reference topics: SD-Access edge node, anycast gateway, endpoint registration, virtual networks, fabric policy.

Spanning-tree PortFast must be enabled on interfaces where Wake-on-LAN clients reside so the PCs become reachable immediately when they power on. WoL depends on a sleeping endpoint receiving a magic packet, and once the device wakes, it must be able to send and receive traffic without waiting through traditional STP listening and learning states. Cisco campus designs commonly enable PortFast on access ports connected to end hosts so those ports transition directly to forwarding. That reduces login, DHCP, and application delays after a host becomes active. The NIC and system firmware must support WoL, but the option stating that WoL should be disabled in BIOS is technically wrong. IP directed broadcast and UDP forwarding are relevant when WoL packets must cross routed boundaries, but the answer options here focus on a single action to prevent client-side delay. Disabling directed broadcast or forward protocol would work against remote WoL operation. Reference topics: Wake-on-LAN, PortFast, access-layer design, STP edge ports, client startup convergence.

Multiple Spanning Tree is the correct technology for a large Layer 2 domain with hundreds of switches and VLANs when the goals are efficient link use, loop prevention, and low CPU and memory impact. MST maps multiple VLANs into a smaller number of spanning-tree instances, allowing the designer to load-balance groups of VLANs across alternate paths without running a separate STP instance for every VLAN. Cisco Rapid PVST+ improves convergence compared with classic STP, but it maintains a separate instance per VLAN, which becomes costly at scale. PVST+ has similar per-VLAN scaling concerns and slower convergence behavior than rapid variants. Plain RSTP improves convergence but does not provide the same VLAN-to-instance mapping flexibility for hundreds of VLANs. MST is standards-based and particularly useful in multivendor environments where VLAN grouping and predictable root placement are required. The design should define MST regions consistently, map VLANs deliberately to instances, place roots near the Layer 3 gateway, and keep the number of instances small enough to protect supervisor CPU and memory. Reference topics: MST, RSTP, Rapid PVST+, VLAN-to-instance mapping, Layer 2 scalability.