Covers OSPF, IS-IS, and BGP routing protocols, routing policy and traffic control, Ethernet switching and IP multicast, IPv6 fundamentals, and network security and reliability.
20 free sample questions216 in the full practice test
A network administrator at a financial services firm is configuring OSPF between two routers, R1 and R2. After configuration, the OSPF adjacency fails to establish and remains stuck in the ExStart state. A packet capture reveals that R1 and R2 are successfully exchanging Hello packets and agree on all parameters, but they continuously retransmit Database Description (DD) packets to each other. What is the most likely cause of this issue?
Answer and explanation
Correct answer: C
When OSPF routers are in the ExStart/Exchange state, they exchange Database Description (DD) packets to synchronize their Link-State Databases (LSDBs). If the Maximum Transmission Unit (MTU) on their interconnected interfaces is different, the router with the larger MTU might send a DD packet that is too large for the other router to receive. This causes the negotiation to fail and the routers to get stuck in this state, continuously retransmitting DD packets. Mismatched area types or duplicate router IDs would typically prevent the neighbor relationship from forming at all (stuck in 2-Way or earlier).
Question 2
Intermediate
BGP Core Knowledge · BGP Path Attributes
A network engineer is designing a BGP solution for an enterprise with two connections to the same ISP. The goal is to use one connection as the primary path for all outbound traffic and the other as a backup. Which BGP attribute should be configured on the enterprise edge routers to influence the ISP's routing decision for inbound traffic, ensuring the ISP prefers one link over the other?
Answer and explanation
Correct answer: B
The Multi-Exit Discriminator (MED) is an optional non-transitive attribute used to influence how a neighboring AS selects an entry point into your AS when multiple entry points exist. A lower MED value is preferred. By setting a lower MED on the routes advertised over the primary link and a higher MED on the backup link, you suggest to the ISP which path to prefer for inbound traffic. Local Preference is used to influence outbound traffic decisions within your own AS. AS_Path prepending is another method, but MED is specifically designed for this purpose.
Question 3
Advanced
IS-IS Core Knowledge · IS-IS Route Control
A large-scale enterprise network uses IS-IS as its IGP. The network is divided into multiple Level-1 areas connected to a Level-2 backbone. To improve scalability, the lead architect wants to prevent Level-1 routers from receiving specific Level-2 routes while still allowing them to reach those destinations via a default route. Which IS-IS feature should be implemented on the Level-1-2 border routers?
Answer and explanation
Correct answer: B
By default, a Level-1-2 router sets the Attached (ATT) bit in its Level-1 LSP. This signals to other Level-1 routers within the same area that it has a connection to the Level-2 backbone. The Level-1 routers will then install a default route pointing to the L1/L2 router. This mechanism allows Level-1 routers to reach destinations outside their area (including other L1 areas and external routes) without needing to hold all the specific Level-2 routes in their routing tables, thus improving scalability.
Question 4
IntermediateMultiple answers
Routing and Traffic Control · Policy-Based Routing (PBR)
An administrator is implementing Policy-Based Routing (PBR) on a Huawei router to redirect HTTP traffic from a specific subnet (192.168.10.0/24) to a dedicated proxy server (10.10.10.1). Which of the following components are required for this configuration? (Select THREE)
Answer and explanation
Correct answers: A, B, C
Question 5
Beginner
OSPF Core Knowledge · OSPF LSA Types
True or False: In a multi-area OSPF network, a Type 4 Summary-ASBR LSA is generated by an Area Border Router (ABR) to advertise the location of an Autonomous System Boundary Router (ASBR) to other areas.
Answer and explanation
Correct answer: A
This statement is true. A Type 5 External LSA, which advertises an external route, is flooded throughout the OSPF domain. However, the next-hop for this external route is the ASBR. Routers in other areas need to know how to reach the ASBR. The ABR in the ASBR's area generates a Type 4 LSA to advertise the ASBR's router ID and the cost to reach it into other areas, enabling proper routing to external destinations.
Question 6
Advanced
BGP Core Knowledge · BGP Route Aggregation
Case Study: Global Logistics Inc. Network Redesign
Global Logistics Inc. is redesigning its core network, which uses BGP for external connectivity and OSPF as the IGP. The company has a large number of internal routes that are currently being redistributed into BGP. This practice has led to instability in the BGP routing table, as every internal OSPF flap (a link going down or up) causes BGP updates to be sent to their upstream ISPs. This instability is causing performance issues and has violated their SLA with the providers.
The network architecture team has been tasked with resolving this instability. The primary requirement is to advertise a stable summary of the company's internal address space to the internet while preventing IGP instability from affecting the external BGP sessions. The solution must ensure that internal subnets remain reachable from the internet via the advertised summary route. Any solution that requires manual intervention for every internal network change is unacceptable.
The current configuration on the edge routers involves a redistribute ospf command under the BGP process, which is the source of the problem. The company's allocated public IP space is 203.0.113.0/24, which is currently broken down into multiple /26 and /27 subnets used internally and advertised via OSPF.
Which approach best meets the requirements to stabilize BGP while maintaining reachability?
Answer and explanation
Correct answer: D
This is the best practice for BGP stability. By advertising only a single, stable aggregate route, the external BGP peers are shielded from any instability within the internal OSPF domain. The aggregate route will only be withdrawn if all contributing specific routes disappear, which is a much more significant event than a single link flap. This solves the instability problem while ensuring reachability and avoiding the high administrative overhead of static routes. Route dampening punishes flapping routes but doesn't solve the core issue of over-advertisement. Filtering after redistribution is less efficient and doesn't stop the BGP process from reacting to IGP churn.
Question 7
Intermediate
Network Security Basics · Switch Security
A network administrator is securing the access layer of a campus network using Huawei switches. To prevent common attacks like DHCP starvation and rogue DHCP servers, DHCP Snooping has been enabled. Which additional feature must be configured to validate ARP packets against the DHCP Snooping binding database, preventing ARP spoofing attacks?
Answer and explanation
Correct answer: C
Dynamic ARP Inspection (DAI) is a security feature that works in conjunction with DHCP Snooping. It intercepts all ARP requests and replies on untrusted ports and validates them against the IP-to-MAC address bindings stored in the DHCP Snooping database. If an ARP packet does not have a valid binding, it is dropped. This effectively prevents ARP spoofing and man-in-the-middle attacks.
To ensure rapid failure detection for a critical link carrying BGP traffic between two routers, an engineer configures BFD. The desired detection time is less than one second. Which BFD parameters are most directly configured to achieve this goal?
Answer and explanation
Correct answer: D
The speed of BFD failure detection is determined by the negotiated transmission interval and the detection multiplier. The min-tx-interval specifies the minimum interval at which the local system wants to transmit BFD packets, min-rx-interval is the minimum interval at which it can receive them, and the detect-multiplier is the number of consecutive packets that can be missed before the session is declared down. The actual detection time is the negotiated transmit interval multiplied by the neighbor's detect-multiplier. Configuring these values aggressively (e.g., 50ms intervals with a multiplier of 3) achieves sub-second detection.
Question 9
IntermediateMultiple answers
Large-scale WLAN Architecture · CAPWAP Protocol
A university is deploying a large-scale campus WLAN using Huawei's Fit AP architecture. The network consists of one Access Controller (AC) and hundreds of Access Points (APs). How do the APs discover the location of the AC to establish a CAPWAP tunnel? (Select TWO methods)
Answer and explanation
Correct answers: A, C
Question 10
IntermediateMultiple answers
Switching Core Knowledge · Spanning Tree Protocols
An engineer is configuring MSTP on a set of interconnected Huawei switches. To ensure that switches are part of the same MSTP region, which three parameters must match exactly on all switches within that region?
Answer and explanation
Correct answers: A, B, C
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