350-401 Architecture Practice Question
A network administrator is deploying a new branch office that requires a redundant default gateway for hosts on VLAN 10. The administrator wants to use a Cisco-proprietary protocol that provides sub-second failover and supports load sharing between two routers. Which First Hop Redundancy Protocol should be used?
⚠ Common exam trap
The trap here is assuming that HSRP provides load sharing by default, when in fact it requires multiple groups and is not inherently load-balancing.
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)
Gateway Load Balancing Protocol (GLBP) is the correct choice because it is Cisco-proprietary and provides both redundancy and load sharing. Unlike HSRP, which has a single active router, GLBP uses an Active Virtual Gateway to distribute traffic across multiple Active Virtual Forwarders, each with its own virtual MAC address. This allows hosts to share the load while maintaining sub-second failover.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Hot Standby Router Protocol (HSRP)
Why it's wrong here
HSRP is Cisco-proprietary and provides sub-second failover, but it does not natively support load sharing across multiple routers in a single group. Only one router is active and forwards traffic; the standby router takes over upon failure. While multiple HSRP groups can be used for load sharing, the protocol itself does not inherently balance traffic across routers in the same group.
- ✗
Virtual Router Redundancy Protocol (VRRP)
Why it's wrong here
VRRP is an open standard, not Cisco-proprietary. It provides redundancy and can be configured for load sharing using multiple VRRP groups, but the question specifically asks for a Cisco-proprietary protocol. VRRP is widely supported across vendors, but it does not meet the proprietary requirement. Additionally, its failover time can be sub-second with tuning, but that is not its defining characteristic.
- ✓
Gateway Load Balancing Protocol (GLBP)
Why this is correct
GLBP is a Cisco-proprietary First Hop Redundancy Protocol that provides both redundancy and load sharing. It uses an Active Virtual Gateway (AVG) and up to four Active Virtual Forwarders (AVFs). The AVG assigns virtual MAC addresses to each AVF, and hosts are distributed across the AVFs for load balancing. Failover is sub-second, and if an AVF fails, another AVF takes over its virtual MAC address.
- ✗
Intermediate System to Intermediate System (IS-IS)
Why it's wrong here
IS-IS is a routing protocol, not a First Hop Redundancy Protocol. It is used to exchange routing information between routers and does not provide a virtual default gateway for hosts. While IS-IS can converge quickly, it does not offer the redundancy and load sharing features required for a default gateway. Using IS-IS would not fulfill the requirement for a redundant gateway.
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
SDN Controllers and Cisco ACI
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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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
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