Free Practice Questions for Cisco 300-420 Exam

VRF-Lite with OSPF satisfies the requirements because it creates multiple isolated Layer 3 routing tables without requiring a service-provider MPLS core or specialized hardware. Each VRF has its own forwarding table, interfaces, and route exchange process, so overlapping IP address space can exist in different virtual networks. When communication between segments is required, the design can use controlled route leaking, a firewall, or a shared-services VRF. OSPF can run per VRF to exchange routes within each isolated segment using widely supported routing technology. VSS, vPC, and plain 802.1Q with HSRP can improve Layer 2 or device redundancy, but they do not provide independent Layer 3 routing tables with overlapping addressing. A multihop MPLS design can also support many VPNs, but it is more complex and beyond the stated need for widely available technologies without specialized equipment. VRF-Lite is therefore the correct enterprise campus segmentation choice. Reference topics: VRF-Lite, virtual routing and forwarding, inter-VRF routing, overlapping IP address support, campus segmentation.

Dual stack is the migration topology that supports IPv6 while preserving existing IPv4 services during the transition. In a dual-stack design, hosts and network devices run IPv4 and IPv6 in parallel, allowing applications and services to move gradually from IPv4 to IPv6 without forcing an immediate cutover. That matches the customer’s plan: keep the current IPv4 topology and services, introduce IPv6 connectivity, migrate services, and eventually decommission the IPv4 topology. 6VPE is used to carry IPv6 VPN routes across an MPLS IPv4 provider core, which is a service-provider VPN use case rather than a general enterprise migration topology. 6to4 is an automatic tunneling mechanism and is not appropriate as a stable enterprise migration plan. NAT64 enables IPv6-only clients to reach IPv4 resources through translation, but it does not preserve the complete IPv4 topology while services migrate. Cisco migration guidance treats dual stack as the cleanest operational model when infrastructure supports both protocols, because it avoids translation side effects and allows DNS and application behavior to determine which protocol is used.

Contracting an internet connection and deploying DMVPN is the most practical solution when the enterprise needs a fast, affordable, and reliable backup for a single MPLS provider. DMVPN can use broadband internet transport to build encrypted GRE/IPsec tunnels between sites, providing a backup WAN path without waiting for another private MPLS provider circuit. It supports dynamic routing and can be deployed incrementally, which makes it suitable after a recent outage when time and cost matter. BFD echo mode toward a provider PE can improve failure detection, but it does not create an alternate transport if the only MPLS provider has an outage. Adding a WAN router and a floating static route also fails unless another path exists. Contracting a second MPLS provider and deploying GETVPN may be robust, but it is slower and more expensive than the requested quick and affordable backup. Reference topics: DMVPN backup WAN, MPLS resiliency, internet VPN, IPsec, branch availability, rapid WAN deployment.