CCIE CCIE Network Design 1 — Questions and Answers
Question 1: In the Cisco hierarchical network design model, which layer is responsible for routing between VLANs and applying QoS policies before traffic enters the core?
- Core layer
- Distribution layer (Correct answer)
- Access layer
- Collapsed core layer
Correct answer: Distribution layer
The distribution layer aggregates access-layer traffic, performs inter-VLAN routing, and applies QoS and policy enforcement before handing off to the core.
Question 2: Which design approach uses a single routing process to provide both intra-area fast convergence and scalability across multiple areas in OSPF?
- Flat OSPF with area 0 only
- Hierarchical OSPF with multiple areas (Correct answer)
- OSPF stub areas replacing all non-backbone areas
- OSPF with all routers as ABRs
Correct answer: Hierarchical OSPF with multiple areas
Hierarchical OSPF with multiple areas limits LSA flooding scope per area, enabling fast local convergence while backbone area 0 provides scalability across the domain.
Question 3: A network designer is choosing between VSS and StackWise Virtual for a campus core. What is the primary design advantage of VSS/StackWise Virtual over traditional dual-chassis designs using HSRP?
- Lower hardware cost per chassis
- Elimination of STP blocked ports by enabling active-active forwarding (Correct answer)
- Support for more VLANs per switch
- Simplified SNMP trap configuration
Correct answer: Elimination of STP blocked ports by enabling active-active forwarding
VSS and StackWise Virtual create a single logical switch that allows both uplinks to forward traffic simultaneously, eliminating STP-blocked ports and doubling usable bandwidth.
Question 4: When designing a WAN with diverse provider circuits for redundancy, which BGP attribute should be manipulated on inbound traffic to prefer one ISP over another without changing outbound path selection?
- LOCAL_PREF
- MED (MULTI_EXIT_DISC) (Correct answer)
- AS_PATH prepending
- WEIGHT
Correct answer: MED (MULTI_EXIT_DISC)
MED is advertised to neighboring ASes to suggest a preferred entry point into your AS, influencing how external providers forward traffic to you on inbound paths.
Question 5: In a spine-leaf data center fabric design, what is the maximum number of hops between any two endpoints regardless of the fabric size?
- 1 hop
- 2 hops
- 3 hops (Correct answer)
- 4 hops
Correct answer: 3 hops
In spine-leaf, any endpoint connects to a leaf, traffic crosses one spine, and reaches the destination leaf — always exactly 3 hops, ensuring consistent, predictable latency.
Question 6: A designer needs to segment a campus network so that finance and HR traffic is isolated at Layer 3 without deploying separate physical switches. Which technology best satisfies this requirement?
- Private VLANs (PVLAN)
- VRF-Lite (Correct answer)
- VLAN pruning on trunks
- Port-based VLAN ACLs
Correct answer: VRF-Lite
VRF-Lite creates multiple independent routing tables on a single router or Layer 3 switch, providing complete Layer 3 isolation between departments without additional hardware.
Question 7: Which design principle should be prioritized when sizing redundant power supplies and cooling in a network equipment room to meet 'five nines' (99.999%) availability?
- N redundancy (one spare total)
- N+1 redundancy (one spare per component)
- 2N redundancy (fully duplicated systems) (Correct answer)
- N-1 redundancy (operate at reduced capacity)
Correct answer: 2N redundancy (fully duplicated systems)
2N redundancy provides a fully independent duplicate of every power and cooling component, ensuring no single failure — including entire PSU or cooling unit failure — causes downtime.
CCIE CCIE Network Design 1
In the Cisco hierarchical network design model, which layer is responsible for routing between VLANs and applying QoS policies before traffic enters the core?