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

A /22 subnet is the smallest IPv4 block in the answer set that closely fits a branch expected not to exceed roughly one thousand users while avoiding unnecessary address waste. A /22 contains 1024 total addresses and 1022 usable host addresses after the network and broadcast addresses are reserved. That aligns with the requirement to provide the maximum number of host addresses without selecting a larger block than necessary. A /21 provides 2048 total addresses and 2046 usable hosts, which is materially larger than the stated requirement and wastes address space. The specific 192.168.8.0/22 block also aligns on a valid /22 boundary because /22 networks increment by four in the third octet. A 192.168.16.0/22 is also mathematically valid, but the exhibit determines the available address range; the selected option uses the appropriate block from the displayed plan. Reference topics: IPv4 subnet sizing, CIDR, usable host calculation, branch address planning, VLSM.

DMVPN Phase 3 hub-and-spoke is the best design for this requirement. The customer wants secure dynamic site-to-site VPN connectivity for voice, video, and FTP, and also wants branches to communicate directly instead of hairpinning all traffic through headquarters. DMVPN supports dynamic spoke-to-spoke tunnels using multipoint GRE, NHRP, and IPsec protection. Phase 3 is more scalable than Phase 2 because the hub can send NHRP redirect messages and spokes can install shortcut routes, reducing the need for every spoke to maintain detailed next-hop information for every other spoke. That is important because the branch routers have limited memory. Phase 1 is hub-and-spoke only and does not provide dynamic spoke-to-spoke forwarding. A hierarchical Phase 3 design can be useful at very large scale, but the question describes a headquarters and remote branch design rather than multiple tiers of hubs. Phase 3 hub-and-spoke satisfies direct branch communication, security, and scale. Reference topics: DMVPN Phase 3, NHRP redirect, spoke-to-spoke tunnels, IPsec encryption, branch WAN scalability.

Scalable groups provide intra-VN traffic filtering and control in Cisco SD-Access. Within a virtual network, macro segmentation separates routing tables, but endpoints inside the same VN may still need policy control based on identity, role, or security posture. Cisco SD-Access uses scalable group tags and scalable group ACLs to implement group-based policy. This allows policy to be expressed as user or device group relationships instead of only subnet-based ACL entries. The result is microsegmentation inside the virtual network, where traffic between groups can be permitted or denied consistently across the fabric. MAC ACLs are limited Layer 2 filters and do not provide the identity-based policy model required for SD-Access. Prefix lists are route-filtering tools, not intra-VN access-control mechanisms. Service policies are used for QoS or traffic treatment and do not define group-based segmentation. Scalable groups are therefore the correct policy construct for intra-VN filtering in the fabric. Reference topics: Cisco SD-Access policy, scalable groups, SGT, SGACL, microsegmentation, intra-VN control.