Network Architecture: BGP, OSPF, EVPN, VXLAN

Trace an application packet across switched and routed hops, identifying the L2, L3, and L4 fields that change at each boundary.

Distinguish the control, data, and management planes in a modern network device and identify common failure symptoms in each plane.

Convert a business connectivity brief into measurable network requirements, constraints, assumptions, and risks.

Identify failure domains and convergence boundaries in a proposed network topology.

Calculate end-to-end service availability from the availability of serial and redundant network components.

Create a vendor-neutral logical network diagram that clearly represents addressing, routing domains, segmentation, and dependencies.

Create a physical network diagram that clearly represents device roles, links, bandwidth, and redundancy.

Apply a layered troubleshooting workflow to localize a connectivity failure before selecting device-level commands.

Select an access-distribution-core, collapsed-core, or routed-access campus topology from stated scale and resilience requirements.

Determine spanning-tree forwarding and blocking behavior from a campus topology, bridge priorities, and link costs.

Compare stacking, multi-chassis link aggregation, and routed-access designs by failure domain, convergence, and operational complexity.

Design VLAN and VRF segmentation for users, infrastructure, guests, voice, and management services.

Select a first-hop gateway design that meets stated availability and convergence requirements.

Design OSPF areas, interface types, summarization boundaries, and passive interfaces for a multi-building campus.

Design a dual-stack IPv4/IPv6 addressing and gateway plan for a campus network.

Diagnose a campus outage by correlating MAC, ARP/ND, spanning-tree, link-aggregation, and routing state.

Compare leased-line, Internet VPN, carrier Ethernet, MPLS VPN, and SD-WAN transports against business requirements.

Design a controlled OSPF-to-BGP routing boundary without unintended route feedback.

Construct a BGP import and export policy using prefixes, AS paths, communities, local preference, MED, and prepending.

Design deterministic inbound and outbound path selection for a dual-homed enterprise site.

Design route summarization and default-route policies that limit failure propagation across an enterprise WAN.

Explain how SD-WAN orchestration, tunnels, path measurement, and application-aware policy form an overlay service.

Create a WAN QoS policy that maps application classes to marking, queuing, shaping, and policing behavior.

Localize WAN black holes, asymmetric paths, fragmentation, and MTU-related failures from packet and routing evidence.

Classify data-center traffic requirements as east-west, north-south, storage, management, or service-chain traffic.

Design a leaf-spine topology that provides predictable hop count and equal-cost multipath forwarding.

Create a scalable point-to-point and loopback addressing plan for a routed data-center underlay.

Select OSPF, IS-IS, or eBGP for a data-center underlay based on scale, convergence, and operational requirements.

Design resilient single-homed, dual-homed, and port-channel server attachments to leaf switches.

Trace an endpoint packet through underlay and overlay forwarding in a leaf-spine fabric.

Calculate fabric oversubscription and identify links that constrain expected traffic demand.

Compare centralized and distributed default-gateway placement for a data-center fabric.

Encapsulate an Ethernet frame conceptually in VXLAN and identify the purpose of the VNI, VTEP, and UDP fields.

Explain how the MP-BGP EVPN address family distributes overlay reachability between VTEPs.

Differentiate L2 VNIs and L3 VNIs and map each to bridge domains and tenant routing instances.

Trace the advertisement and import of an EVPN type-2 MAC/IP route between VTEPs.

Explain how EVPN type-3 routes support discovery and handling of broadcast, unknown-unicast, and multicast traffic.

Trace an IP prefix advertised between tenant routing instances using an EVPN type-5 route.

Compare symmetric and asymmetric integrated routing and bridging packet flows.

Assign route distinguishers and route targets that produce the intended EVPN route uniqueness and import policy.

Explain how Ethernet segments, designated forwarder election, aliasing, and split-horizon behavior support EVPN multihoming.

Trace host mobility through MAC/IP route updates and anycast-gateway forwarding.

Explain how ARP and IPv6 neighbor-discovery suppression reduce flooding in an EVPN-VXLAN fabric.

Design route-reflector placement and address-family policy for a resilient EVPN control plane.

Localize an EVPN-VXLAN failure to underlay reachability, BGP peering, route advertisement, or route import.

Diagnose VXLAN data-plane loss using VNI, VTEP, MAC, ARP/ND, routing, and tunnel state.

Design a data-center interconnect that preserves explicit failure domains and avoids uncontrolled L2 extension.

Evaluate control-plane protection, tenant isolation, and operational guardrails for an EVPN-VXLAN fabric.

Analyze a TCP or UDP flow using ports, connection state, handshake behavior, retransmissions, and timeouts.

Trace source NAT, destination NAT, and port translation through a stateful network path.

Construct a zone-based stateful firewall policy from application flows and least-privilege requirements.

Trace how DHCP, DNS, and IP address management dependencies affect endpoint connectivity.

Trace an HTTP request through DNS resolution, TCP establishment, TLS negotiation, and application response.

Select a load-balancing algorithm, health check, and persistence method for a stated application requirement.

Differentiate forward proxies, reverse proxies, web application firewalls, and application delivery controllers by function.

Diagnose service-chain failures caused by asymmetric routing, stale state, failed health checks, or incorrect address translation.

Differentiate provider access, aggregation, edge, and core roles in a service-provider topology.

Design IS-IS level boundaries, adjacencies, metrics, and route-leaking behavior for a provider core.

Trace an IP packet across an MPLS label-switched path using label push, swap, and pop operations.

Compare LDP and segment-routing MPLS as methods for establishing transport paths.

Trace VPNv4 or VPNv6 route distribution between provider-edge routers using MP-BGP.

Assign VRFs, route distinguishers, and route targets for an isolated MPLS Layer 3 VPN service.

Compare pseudowire, VPLS, and EVPN approaches to delivering provider Layer 2 services.

Select fast-reroute and traffic-engineering mechanisms for stated provider convergence and path-control requirements.

Design a route-reflector hierarchy that meets stated scale, redundancy, and path-diversity requirements.

Explain how originator IDs and cluster lists prevent route-reflection loops.

Create a scalable routing policy using standard, extended, and large BGP communities.

Predict BGP best-path changes produced by local preference, AS-path length, origin, MED, and IGP cost.

Design prefix aggregation, maximum-prefix limits, and route filters that reduce routing risk.

Compare BFD, BGP Prefix Independent Convergence, graceful restart, and additional-path advertisement by failure behavior.

Validate a received Internet prefix using RPKI route-origin authorization states.

Localize a BGP reachability fault by comparing received routes, policy results, selected paths, and installed forwarding entries.

Map virtual networks, subnets, route tables, security controls, gateways, and load balancers to their on-premises networking equivalents.

Predict packet forwarding from cloud route-table priority, longest-prefix matching, and platform-specific routing constraints.

Select a hub-and-spoke, transit, or distributed cloud network topology from scale and isolation requirements.

Compare site-to-site VPN and private-cloud connectivity by bandwidth, availability, latency, and cost.

Design redundant BGP routing and failure handling between an enterprise network and a cloud provider.

Trace traffic through cloud NAT, firewall, and load-balancing services.

Compare direct, carrier-mediated, and cloud-native patterns for multi-cloud connectivity.

Localize a hybrid connectivity failure across on-premises routing, tunnels or circuits, cloud routes, and security policy.

Represent network inventory, interface, addressing, and routing data in structured YAML and JSON.

Retrieve and interpret network state through a REST API.

Write a small Python program that parses structured network state and flags a stated violation.

Generate vendor-specific configuration snippets from a vendor-neutral template and structured data.

Apply an idempotent configuration change to a defined device group using an automation workflow.

Use a source-of-truth model to detect intended-state and operational-state drift.

Create automated pre-change and post-change tests for reachability, routing, redundancy, and policy.

Select logs, SNMP metrics, streaming telemetry, flow records, and packet captures for a stated observability requirement.

Convert a stakeholder brief into a requirements, assumptions, constraints, and risks register.

Select campus, WAN, data-center, provider, and cloud connectivity patterns that satisfy a stated business scenario.

Create a high-level design showing sites, fabrics, routing domains, security zones, services, and external dependencies.

Create a low-level addressing, segmentation, routing-policy, and protocol plan for a bounded part of the design.

Build a failure-mode matrix that maps component failures to impact, detection, convergence target, and mitigation.

Estimate bandwidth, port, route, and endpoint capacity with documented growth assumptions.

Create a phased migration and rollback plan that maintains service continuity.

Create an architecture validation plan with acceptance tests, telemetry, ownership, and operational handoff criteria.