CCNA IP Routing Practice Question
A network administrator has configured HSRP between RouterA and RouterB for VLAN 10. End hosts using the virtual IP 192.168.1.1 as their default gateway experience intermittent connectivity losses, and pings to 192.168.1.1 often fail. The output of 'show standby brief' on both routers shows the state as Active. What is the most likely cause?
⚠ Common exam trap
Cisco often tests the concept that HSRP authentication mismatches cause a dual-active failure, while candidates may incorrectly assume that equal priorities or group number 0 are the root cause.
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
✓
The routers are configured with mismatched HSRP authentication methods.
When both routers show the HSRP state as Active, a 'dual-active' scenario exists, which causes intermittent connectivity because both routers forward traffic for the virtual IP. Mismatched HSRP authentication methods (e.g., one router using plain-text authentication and the other using MD5) prevent the routers from exchanging proper Hello messages, so they fail to negotiate a single Active router. This is the most likely cause because authentication mismatches break the HSRP adjacency, leading to both routers assuming the Active role.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
The virtual IP address is configured on only one router.
Why it's wrong here
If the virtual IP is only on one router, that router would become Active and the other would either stay Init or Standby (if it learns of a higher priority), but not both Active. The symptom would be a single point of failure, not intermittent connectivity with both showing Active.
- ✓
The routers are configured with mismatched HSRP authentication methods.
Why this is correct
Mismatched authentication (e.g., MD5 vs. text) causes each router to disregard the other's HSRP hellos. Each then assumes no peers exist and becomes Active, leading to both routers claiming the virtual IP and MAC, which results in ARP table flapping and intermittent connectivity.
- ✗
The HSRP group number on one router is set to 0.
Why it's wrong here
Group 0 is a valid HSRPv2 group number. Even if group numbers were mismatched, the routers would belong to different HSRP groups and would not both be Active for the same virtual IP. They would instead form independent standby groups with distinct virtual IPs.
- ✗
The priority on both routers is configured to the same value.
Why it's wrong here
Equal priorities result in the router with the higher IP address becoming Active, and the other becoming Standby, as per HSRP election rules. This does not cause a dual-Active condition and would not produce intermittent connectivity.
Option-by-option analysis
Why each answer is right or wrong
Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The 200-301 exam frequently reuses these exact scenarios with slightly different constraints.
✓The routers are configured with mismatched HSRP authentication methods.Correct answer▾
Why this is correct
Mismatched authentication (e.g., MD5 vs. text) causes each router to disregard the other's HSRP hellos. Each then assumes no peers exist and becomes Active, leading to both routers claiming the virtual IP and MAC, which results in ARP table flapping and intermittent connectivity.
✗The virtual IP address is configured on only one router.Wrong answer — click to see why▾
Why this is wrong here
A missing virtual IP on one router does not cause both to be Active; the router without the virtual IP cannot claim the Active role for that address.
✗The HSRP group number on one router is set to 0.Wrong answer — click to see why▾
Why this is wrong here
A group number mismatch does not cause both routers to appear as Active for the same virtual IP; they would be in separate groups.
✗The priority on both routers is configured to the same value.Wrong answer — click to see why▾
Why this is wrong here
Equal priority does not lead to multiple Active routers; HSRP uses the interface IP address as a tiebreaker to elect a single Active router.
Analysis generated from the official 200-301blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”
Visual reference
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Related to this question
Learn chapter
OSPFv3 Single-Area Configuration for IPv6
Key term
VLAN
A VLAN (Virtual Local Area Network) is a logical grouping of network devices that behave as if they are on the same physical network segment, regardless of their actual physical location.
Key term
HSRP
HSRP stands for Hot Standby Router Protocol, a Cisco proprietary protocol that allows multiple routers to work together as a single virtual router to provide default gateway redundancy.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 200-301 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 200-301 exam.