This 200-301 practice question tests your understanding of ip routing. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
Network Topology
You are connected to R1. The network requires HSRP for default gateway redundancy on subnet 192.168.1.0/24. R2 should be the active router, and R1 the standby. Currently, both routers show as active. Configure R1 with priority 90, enable preempt, ensure the virtual IP is 192.168.1.254, and configure tracking of interface GigabitEthernet0/1 (subnet 203.0.113.0/30) so that if R1's tracked interface goes down, its priority decreases by 20. Verify the final state with 'show standby brief'.
R1# show running-config | section interface GigabitEthernet0/0
interface GigabitEthernet0/0
ip address 192.168.1.1 255.255.255.0
standby version 2
standby 1 ip 192.168.1.254
standby 1 priority 100
standby 1 preempt
!
interface GigabitEthernet0/1
ip address 203.0.113.1 255.255.255.252
no shutdown
!
R1# show standby brief
P indicates configured to preempt.
|
Interface Grp Pri P State Active Standby Virtual IP
Gi0/0 1 100 Active local 192.168.1.2 192.168.1.254
R2# show standby brief
P indicates configured to preempt.
|
Interface Grp Pri P State Active Standby Virtual IP
Gi0/0 1 100 Active 192.168.1.1 local 192.168.1.254
This configuration correctly sets R1's HSRP priority to 90, enables preempt, and tracks interface GigabitEthernet0/1 with a decrement of 20. With priority 90, R1 becomes standby (R2 with default priority 100 becomes active). If the tracked interface fails, priority drops to 70, ensuring R2 remains active.
Why wrong: This is incorrect because setting priority to 110 makes R1 the active router (higher priority than R2's default 100), but the requirement is for R2 to be active. The priority should be lower than R2's.
Why wrong: This is incorrect because the decrement value is 30, but the requirement specifies a decrement of 20. Using 30 would cause an excessive priority drop, potentially causing unnecessary failover.
Why wrong: This is incorrect because the tracked interface is GigabitEthernet0/0 (the HSRP interface itself), but the requirement specifies tracking of GigabitEthernet0/1. Tracking the HSRP interface is invalid and would not achieve the desired behavior.
The scenario requires R2 to be the HSRP active router. By default, both routers have priority 100, and HSRP election would select the router with the higher IP address as active if priorities are equal. To ensure R2 becomes active, R1's priority must be lowered to 90. Additionally, tracking interface GigabitEthernet0/1 with a decrement of 20 is configured so that if R1's uplink fails, its priority drops to 70, further preventing it from becoming active. The correct configuration on R1 sets priority 90, enables preempt, and tracks the correct interface with decrement 20. Options B, C, and D are wrong because: B sets a higher priority (110) which would make R1 active; C uses an incorrect decrement of 30; and D tracks the wrong interface (Gig0/0 instead of Gig0/1).
Key principle: Count usable hosts — not total addresses — and remember that the network and broadcast addresses are not available to hosts in standard IPv4 subnets.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
This configuration correctly sets R1's HSRP priority to 90, enables preempt, and tracks interface GigabitEthernet0/1 with a decrement of 20. With priority 90, R1 becomes standby (R2 with default priority 100 becomes active). If the tracked interface fails, priority drops to 70, ensuring R2 remains active.
This is incorrect because setting priority to 110 makes R1 the active router (higher priority than R2's default 100), but the requirement is for R2 to be active. The priority should be lower than R2's.
This is incorrect because the decrement value is 30, but the requirement specifies a decrement of 20. Using 30 would cause an excessive priority drop, potentially causing unnecessary failover.
This is incorrect because the tracked interface is GigabitEthernet0/0 (the HSRP interface itself), but the requirement specifies tracking of GigabitEthernet0/1. Tracking the HSRP interface is invalid and would not achieve the desired behavior.
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.
This configuration correctly sets R1's HSRP priority to 90, enables preempt, and tracks interface GigabitEthernet0/1 with a decrement of 20. With priority 90, R1 becomes standby (R2 with default priority 100 becomes active). If the tracked interface fails, priority drops to 70, ensuring R2 remains active.
✗interface GigabitEthernet0/0
standby version 2
standby 1 ip 192.168.1.254
standby 1 priority 110
standby 1 preempt
standby 1 track GigabitEthernet0/1 20Wrong answer — click to see why▾
Why this is wrong here
The priority value is higher than the default, which would make R1 active instead of standby.
Why candidates choose this
Candidates may think increasing priority ensures redundancy, but the requirement specifies R2 as active, so R1's priority must be lower.
✗interface GigabitEthernet0/0
standby version 2
standby 1 ip 192.168.1.254
standby 1 priority 90
standby 1 preempt
standby 1 track GigabitEthernet0/1 30Wrong answer — click to see why▾
Why this is wrong here
The decrement value does not match the required 20; it is 30.
Why candidates choose this
Candidates may confuse the decrement value or think a larger decrement provides better failover, but the exact value must match the requirement.
✗interface GigabitEthernet0/0
standby version 2
standby 1 ip 192.168.1.254
standby 1 priority 90
standby 1 preempt
standby 1 track GigabitEthernet0/0 20Wrong answer — click to see why▾
Why this is wrong here
The tracked interface is wrong; it should be GigabitEthernet0/1, not GigabitEthernet0/0.
Why candidates choose this
Candidates may mistakenly track the HSRP interface thinking it monitors the HSRP state, but tracking should be on an upstream interface to detect connectivity loss.
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?”
Common exam traps
Common exam trap: usable hosts are not the same as total addresses
Subnetting questions often tempt you into counting all addresses. In normal IPv4 subnets, the network and broadcast addresses are not usable host addresses.
Detailed technical explanation
How to think about this question
Subnetting questions test whether you can identify the network, broadcast address, usable range, mask and correct subnet. Slow down enough to calculate the block size correctly.
KKey Concepts to Remember
CIDR notation defines the prefix length.
Block size helps identify subnet boundaries.
Network and broadcast addresses are not usable hosts in normal IPv4 subnets.
The required host count determines the smallest suitable subnet.
TExam Day Tips
→Write the block size before choosing the subnet.
→Check whether the question asks for hosts, subnets or a specific address range.
→Do not confuse /24, /25, /26 and /27 host counts.
Key takeaway
Count usable hosts — not total addresses — and remember that the network and broadcast addresses are not available to hosts in standard IPv4 subnets.
Real-world example
How this comes up in practice
A network engineer segments a warehouse floor into three subnets: 20 scanners, 5 printers, and 2 management hosts. Picking the wrong mask wastes addresses or leaves too few usable hosts. Exam questions test whether you can apply CIDR notation, calculate block size, and identify the correct usable-host range for a given prefix.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this 200-301 question in full detail.
Review block sizes, usable host formulas (2^n − 2), and how to find network and broadcast addresses for /24 through /30. Then practise related 200-301 subnetting questions on CIDR, address ranges, and subnet selection.
IP Routing — This question tests IP Routing — CIDR notation defines the prefix length..
What is the correct answer to this question?
The correct answer is: interface GigabitEthernet0/0
standby version 2
standby 1 ip 192.168.1.254
standby 1 priority 90
standby 1 preempt
standby 1 track GigabitEthernet0/1 20 — The scenario requires R2 to be the HSRP active router. By default, both routers have priority 100, and HSRP election would select the router with the higher IP address as active if priorities are equal. To ensure R2 becomes active, R1's priority must be lowered to 90. Additionally, tracking interface GigabitEthernet0/1 with a decrement of 20 is configured so that if R1's uplink fails, its priority drops to 70, further preventing it from becoming active. The correct configuration on R1 sets priority 90, enables preempt, and tracks the correct interface with decrement 20. Options B, C, and D are wrong because: B sets a higher priority (110) which would make R1 active; C uses an incorrect decrement of 30; and D tracks the wrong interface (Gig0/0 instead of Gig0/1).
What should I do if I get this 200-301 question wrong?
Review block sizes, usable host formulas (2^n − 2), and how to find network and broadcast addresses for /24 through /30. Then practise related 200-301 subnetting questions on CIDR, address ranges, and subnet selection.
What is the key concept behind this question?
CIDR notation defines the prefix length.
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