300-420 Exam Dumps : Designing Cisco Enterprise Networks (ENSLD) v1.1

L2VPN is the correct technology because the requirement is for two remote offices to share a common broadcast domain across a private WAN with minimal overhead. A Layer 2 VPN service extends Ethernet or VLAN connectivity between customer sites while keeping the customer routing design independent of the provider core. From the customer perspective, the two sites can appear to be on the same Layer 2 segment, which satisfies the shared broadcast-domain requirement. GET VPN, IPsec, and GRE are Layer 3-oriented technologies. They can connect sites securely or provide tunneling, but they do not natively create a common Layer 2 broadcast domain between the offices. GRE also adds additional encapsulation overhead, and IPsec alone generally provides encrypted routed connectivity rather than an Ethernet service. For a simple direct logical path over a private WAN, an L2VPN service such as VPWS or VPLS is the appropriate design family. Reference topics: L2VPN, VPWS, VPLS, Ethernet WAN services, broadcast-domain extension, private WAN connectivity.

The correct IS-IS design combines tuned SPF/PRC behavior with a proper Level 1 and Level 2 hierarchy. Reducing SPF and PRC intervals, within platform and stability limits, helps routers react more quickly to topology changes after a link failure. However, fast timers alone are not enough; the hierarchy must contain instability so physical link flaps in the access layer have limited impact on the rest of the network. Access routers should form Level 1 adjacencies inside their local area, while aggregation routers should operate as Level 1/Level 2 routers to connect the access area to the Level 2 backbone. This design gives access routers a simple local view and uses aggregation as the interarea boundary. Running all access and aggregation routers as L1/L2 across the network increases the size of the backbone and exposes more routers to wider flooding, which is the opposite of the requirement. Redistributing Internet routes into Level 1 is also poor design because it bloats the access area. Therefore, the right choices are C and E. Reference topics: IS-IS hierarchy, L1/L2 design, SPF and PRC tuning, access-layer convergence, fault containment.

In Cisco SD-Access, an intermediate node is an underlay transit device. Its responsibility is to provide IP reachability between fabric edge nodes, border nodes, and other fabric infrastructure roles. Intermediate nodes forward routed underlay traffic and do not perform endpoint registration, endpoint lookup, or VXLAN encapsulation for user traffic. Endpoint-to-location mapping is handled through the fabric control plane, which is based on LISP map-server and map-resolver functions. Fabric edge nodes identify connected endpoints, apply policy, act as anycast gateways, and encapsulate user traffic into VXLAN. Border nodes connect the fabric to external networks and handle traffic entering or leaving the fabric. The intermediate node is therefore comparable to a routed distribution or core transport device in a traditional hierarchical campus, except it is participating in the SD-Access underlay. It must provide stable Layer 3 reachability and appropriate MTU for encapsulated traffic but does not maintain the host tracking database or add security group information to VXLAN headers. The correct function is transporting IP packets between edge and border nodes.