Cisco Designing Enterprise Networks (300‑420 ENSLD) Practice Exams
About the Cisco 300-420 ENSLD exam
Exam at a glance
Professional Concentration tier. CCNP Enterprise design specialty. 55-65 questions, 90 min, scaled scoring (Cisco does not publish a cut score), $300 USD. Valid 3 years with continuing-education credits.
Who this exam targets
ENSLD 300-420 is built for network designers, enterprise architects, and senior engineers moving from "I can configure it" to "I can choose the right topology and justify it to stakeholders". The exam tests design judgment — when to push a routing protocol to its limits versus when to split the design, how to balance cost against resilience, when SD-WAN beats traditional MPLS, and how SD-Access changes the campus.
Domain weighting
- Advanced Addressing and Routing Solutions — 25%
- Advanced Enterprise Campus Networks — 25%
- WAN for Enterprise Networks — 20%
- Network Services — 20%
- Automation — 10%
Prerequisites
Cisco recommends three to five years of hands-on experience implementing and operating enterprise networks. No formal prereqs — you can take 300-420 in any order, but most candidates pass 350-401 ENCOR first to complete CCNP Enterprise. CCNA-level knowledge of routing, switching, and WAN technologies is assumed throughout.
Why take this certification
- Completes CCNP Enterprise. Paired with the 350-401 ENCOR Core exam, 300-420 ENSLD earns the full CCNP Enterprise credential — one of the most recognized professional-level networking certifications worldwide.
- Design-focused career path. Where ENARSI signals an operator, ENSLD signals a designer. The role aligns with senior network engineer, network architect, and pre-sales solutions architect titles, all of which command a meaningful salary premium over implementation-only roles.
- SD-Access and SD-WAN coverage. ENSLD is current with Cisco's software-defined fabric story for both campus (SD-Access) and WAN (SD-WAN / Viptela), so the cert maps to where enterprise networks are actually heading.
- Path to CCIE Enterprise Infrastructure. The CCNP Enterprise credential satisfies the written-exam prerequisite step toward CCIE Enterprise Infrastructure, Cisco's expert-tier networking certification.
What you'll learn in the 300-420 ENSLD exam
ENSLD is a design exam — most questions describe a business scenario with constraints (cost, scale, transport availability, latency, security) and ask you to choose the architecture that fits. Memorizing protocol command syntax will not help; understanding trade-offs will.
Addressing and routing at scale
- IPv4 and IPv6 design: hierarchical addressing plans, summarization boundaries, dual-stack vs translation strategies, IPv6 transition options.
- OSPF design: area types (normal / stub / totally stubby / NSSA), ABR/ASBR placement, summarization, scaling beyond a single area.
- EIGRP design: stub routing, hierarchical summarization, query scoping, comparison against OSPF for given topologies.
- BGP design at scale: iBGP full-mesh vs route reflectors vs confederations, eBGP peering models, multi-homing, policy via communities and local preference.
- Route redistribution: filtering and tagging strategies to prevent loops between IGPs and between IGP and BGP.
Enterprise campus design
- Hierarchical models: 2-tier (collapsed core) vs 3-tier (access / distribution / core), Layer 2 vs Layer 3 boundaries.
- Virtual stacking: StackWise, VSS, and the trade-offs of presenting multiple physical switches as one logical device.
- SD-Access fabric design: control plane (LISP), data plane (VXLAN), policy plane (Cisco TrustSec), fabric edge / border / control nodes, fabric-in-a-box for small sites.
- First-hop redundancy: HSRP, VRRP, GLBP — when each fits and how they interact with Layer 3 access designs.
WAN design
- Traditional WAN: MPLS L3VPN, DMVPN phases, IPsec overlays, GET VPN — pick the right transport for the business need.
- SD-WAN: Cisco SD-WAN (Viptela) architecture — vSmart / vBond / vManage, OMP routing, application-aware policy, transport-independent overlays.
- Hybrid WAN: Internet + MPLS combinations, path preference, transport diversity for resilience and cost.
- QoS at the WAN edge: shaping vs policing, queueing strategies for voice/video over constrained links.
Network services
- QoS architecture: classification and marking at the edge, queueing in the core, end-to-end policy consistency.
- Multicast design: PIM modes (sparse / dense / SSM), RP placement strategies (Static / Auto-RP / BSR / Anycast RP), multicast over the WAN.
- Network services: DNS, DHCP, and IPAM design at enterprise scale — hierarchies, redundancy, integration with Active Directory.
Automation for design validation
- Infrastructure-as-Code concepts applied to design — version-controlled topology and config templates.
- Tooling overview: Ansible, Cisco DNA Center automation APIs, NETCONF/YANG models, Python for design validation scripts.
- When automation enforces a design contract (intent) versus when it merely speeds repetitive change.
How the practice exams help
Each free question and every premium exam mirrors the design-scenario format Cisco uses — a business or technical situation with constraints, four plausible architectural choices, one best answer. Detailed explanations cover not just why the recommended design wins but why the alternatives are weaker, so you learn the trade-off reasoning rather than memorizing answers.
How to prepare for the 300-420 ENSLD exam
ENSLD prep is more about reading and reasoning than configuring devices. A successful strategy blends study, design-thinking practice, and lab validation. Recommended approach:
- Read the official guide (4–5 weeks). Work through the CCNP Enterprise Design ENSLD 300-420 Official Cert Guide from Cisco Press cover to cover. ENSLD is one of the few Cisco exams where the official cert guide is genuinely sufficient as a primary source — the design content does not change as fast as platform features.
- Build small designs in CML (3–4 weeks). Cisco Modeling Labs (CML) lets you spin up the routing, switching, and SD-WAN topologies the exam describes. You do not need to memorize commands, but seeing OSPF summarization, BGP route reflection, and SD-Access fabric topologies behave end-to-end fixes the trade-offs in your head.
- Study SD-Access and SD-WAN deep dives (2 weeks). Both fabrics get heavier representation on recent ENSLD versions than older study material implies. Cisco's SD-Access design guide and the SD-WAN design guides on Cisco's Design Zone are the authoritative sources.
- Practice exams (1–2 weeks). Take timed practice tests to identify weak domains. Detailed explanations on every option teach you the design reasoning, not just the right letter. Aim for consistent 80%+ scores across all six domains before booking the real exam.
Recommended timeline
12–16 weeks of focused study (8–12 hours per week) for engineers with three-plus years of enterprise networking experience. Less-experienced candidates should add another 4–6 weeks for foundational routing and switching review before opening the ENSLD material.
Official resources
Review the official Cisco 300-420 ENSLD exam topics on Cisco Learning Network and the CCNP Enterprise Design ENSLD 300-420 Official Cert Guide from Cisco Press. Cisco's Design Zone hosts the validated design guides ENSLD is built around — bookmark it and use it as the source of truth on campus and WAN architectures.