350-401 Infrastructure Practice Question
A network engineer is implementing a first-hop redundancy protocol on a pair of Cisco switches. The requirement is to provide sub-second failover for IPv4 hosts and to load-balance traffic between the two switches for different VLANs. Which protocol should be used to meet these requirements?
⚠ Common exam trap
The trap here is assuming that HSRP or VRRP can automatically load-balance traffic across multiple switches without additional configuration, but only GLBP provides native load-balancing capabilities.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Gateway Load Balancing Protocol (GLBP)
GLBP is designed to provide both redundancy and load balancing. It elects an Active Virtual Gateway that assigns virtual MAC addresses to up to four Active Virtual Forwarders, allowing multiple switches to share the traffic load while providing sub-second failover. HSRP and VRRP can provide redundancy but require manual configuration for load balancing, and IRDP lacks the necessary features.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
ICMP Router Discovery Protocol (IRDP)
Why it's wrong here
IRDP is a legacy protocol that allows hosts to discover routers dynamically, but it does not provide sub-second failover or load balancing. It relies on ICMP router advertisements and is not suitable for high-availability requirements. Modern networks use FHRP protocols like HSRP, VRRP, or GLBP for redundancy and load sharing.
- ✗
Hot Standby Router Protocol (HSRP) version 1
Why it's wrong here
HSRPv1 supports sub-second failover only with millisecond timers, but it does not natively provide load balancing across multiple VLANs without using multiple groups and manual configuration. The requirement for load-balancing between switches for different VLANs is better met by GLBP, which provides automatic load balancing. HSRPv1 also has limited group support.
- ✗
Virtual Router Redundancy Protocol (VRRP) version 3
Why it's wrong here
VRRPv3 supports sub-second failover and is an open standard, but it does not provide native load balancing across multiple routers. While multiple VRRP groups can be configured for load sharing, it requires manual configuration and is not as seamless as GLBP. The requirement for automatic load balancing between switches for different VLANs is not directly satisfied.
- ✓
Gateway Load Balancing Protocol (GLBP)
Why this is correct
GLBP provides both sub-second failover and automatic load balancing across multiple gateways. It uses an Active Virtual Gateway (AVG) and up to four Active Virtual Forwarders (AVFs) to share traffic. Different hosts can be assigned different virtual MAC addresses, distributing the load. This meets the requirements for sub-second failover and load balancing across VLANs without manual per-VLAN group configuration.
Visual reference
Quick reference
Access Control Model Comparison
| Model | Acronym | Who Controls Access? | Best For |
|---|---|---|---|
| Discretionary Access Control | DAC | Resource owner | Small teams, file shares |
| Mandatory Access Control | MAC | System / security labels | Classified govt / military |
| Role-Based Access Control | RBAC | Administrator (via roles) | Enterprise environments |
| Attribute-Based Access Control | ABAC | Policy engine (user + resource attributes) | Fine-grained, dynamic policies |
| Rule-Based Access Control | RuBAC | System rules / ACLs | Firewall rules, network ACLs |
Go deeper
Related to this question
Learn chapter
VLANs and Spanning Tree Protocol Concepts
Key term
HSRP vs VRRP vs GLBP
HSRP, VRRP, and GLBP are network protocols that provide high availability by allowing multiple routers to work together as a single virtual router, ensuring that if one router fails, another automatically takes over without disrupting the network.
Key term
First Hop Redundancy Protocol
A First Hop Redundancy Protocol provides automatic backup for the default gateway router on a network so that devices keep working if the primary router fails.
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JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Cisco exam blueprint
This 350-401 practice question is part of Courseiva's free Cisco certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the 350-401 exam.