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Network Services and Security →mediumConfigurationObjective-mapped

Quick Answer

The correct configuration uses `lease 1` to set a one-day lease, along with the `ip dhcp excluded-address` commands and dotted-decimal subnet masks in the DHCP pool. This works because Cisco IOS interprets the lease value in days when no unit is specified, so `lease 1` equals 24 hours, while `lease 24` would incorrectly create a 24-day lease. Additionally, the `network` command in a DHCP pool requires a dotted-decimal mask like `255.255.255.0`, not CIDR notation like `/24`, which IOS rejects. On the CCNA 200-301 v2 exam, this question tests your ability to configure a DHCP server on a router with subinterfaces, a common real-world scenario for VLAN-based networks. A frequent trap is confusing the lease syntax or using CIDR in the network statement, so always double-check that the lease value matches the required time unit. Memory tip: think of a single day as the number one, not the number twenty-four—keep it simple with `lease 1` for one day.

CCNA Network Services and Security Practice Question

This 200-301 practice question tests your understanding of network services and security. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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
G0/0.10192.168.10.1/24trunkR1SW1

You are connected to R1 via console. R1 is a router that needs to provide DHCP services to hosts on VLAN 10 (192.168.10.0/24) and VLAN 20 (192.168.20.0/24). The router has two subinterfaces on GigabitEthernet0/0: G0/0.10 (192.168.10.1/24) and G0/0.20 (192.168.20.1/24) with 802.1Q encapsulation. Configure R1 as a DHCP server for both VLANs, excluding addresses 192.168.10.1-10 and 192.168.20.1-10, with a lease of 1 day. Ensure DNS server 8.8.8.8 is provided.

Question 1mediumConfiguration
Open the full VLAN trunking answer →

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

✓

ip dhcp excluded-address 192.168.10.1 192.168.10.10 ip dhcp excluded-address 192.168.20.1 192.168.20.10 ip dhcp pool VLAN10 network 192.168.10.0 255.255.255.0 default-router 192.168.10.1 dns-server 8.8.8.8 lease 1 ip dhcp pool VLAN20 network 192.168.20.0 255.255.255.0 default-router 192.168.20.1 dns-server 8.8.8.8 lease 1

Option A correctly uses `lease 1` for a 1-day lease, dotted decimal subnet masks, and proper DHCP pool settings. Option B incorrectly uses CIDR notation `/24` in the network command, which IOS does not accept. Option C uses `lease 24`, which is interpreted as 24 days, not 1 day. Option D also incorrectly uses `lease 24`, resulting in a 24-day lease instead of the required 1-day lease.

Key principle: A trunk being up does not mean the VLAN is allowed across it. Always verify the allowed VLAN list and whether the VLAN exists on both switches.

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

  • ✓

    ip dhcp excluded-address 192.168.10.1 192.168.10.10 ip dhcp excluded-address 192.168.20.1 192.168.20.10 ip dhcp pool VLAN10 network 192.168.10.0 255.255.255.0 default-router 192.168.10.1 dns-server 8.8.8.8 lease 1 ip dhcp pool VLAN20 network 192.168.20.0 255.255.255.0 default-router 192.168.20.1 dns-server 8.8.8.8 lease 1

    Why this is correct

    This configuration correctly creates two DHCP pools for VLAN 10 and VLAN 20, excludes the specified address ranges, sets the default gateway to the subinterface IP, provides DNS server 8.8.8.8, and sets the lease to 1 day. The lease command uses days as the default unit.

    Related concept

    Access ports place end devices into a single VLAN.

  • ✗

    ip dhcp excluded-address 192.168.10.1 192.168.10.10 ip dhcp excluded-address 192.168.20.1 192.168.20.10 ip dhcp pool VLAN10 network 192.168.10.0 /24 default-router 192.168.10.1 dns-server 8.8.8.8 lease 1 0 0 ip dhcp pool VLAN20 network 192.168.20.0 /24 default-router 192.168.20.1 dns-server 8.8.8.8 lease 1 0 0

    Why it's wrong here

    This is incorrect because the 'network' command in DHCP pool configuration requires a subnet mask in dotted decimal format, not CIDR notation (/24). Also, the lease command format '1 0 0' specifies days, hours, minutes; but the correct syntax for 1 day is simply 'lease 1' or 'lease 1 0 0' is acceptable, but the CIDR notation is invalid.

  • ✗

    ip dhcp excluded-address 192.168.10.1 192.168.10.10 ip dhcp excluded-address 192.168.20.1 192.168.20.10 ip dhcp pool VLAN10 network 192.168.10.0 255.255.255.0 default-router 192.168.10.1 dns-server 8.8.8.8 lease 24 ip dhcp pool VLAN20 network 192.168.20.0 255.255.255.0 default-router 192.168.20.1 dns-server 8.8.8.8 lease 24

    Why it's wrong here

    This is incorrect because the lease command expects the lease time in days, not hours. 'lease 24' would be interpreted as 24 days, not 24 hours. To set a lease of 1 day, the correct command is 'lease 1'.

  • ✗

    ip dhcp excluded-address 192.168.10.1 192.168.10.10 ip dhcp excluded-address 192.168.20.1 192.168.20.10 ip dhcp pool VLAN10 network 192.168.10.0 255.255.255.0 default-router 192.168.10.1 dns-server 8.8.8.8 lease 24 ip dhcp pool VLAN20 network 192.168.20.0 255.255.255.0 default-router 192.168.20.1 dns-server 8.8.8.8 lease 24

    Why it's wrong here

    Uses `lease 24` which sets a 24-day lease, not the required 1-day lease. The unit is days.

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.

✓ip dhcp excluded-address 192.168.10.1 192.168.10.10 ip dhcp excluded-address 192.168.20.1 192.168.20.10 ip dhcp pool VLAN10 network 192.168.10.0 255.255.255.0 default-router 192.168.10.1 dns-server 8.8.8.8 lease 1 ip dhcp pool VLAN20 network 192.168.20.0 255.255.255.0 default-router 192.168.20.1 dns-server 8.8.8.8 lease 1Correct answer▾

Why this is correct

This configuration correctly creates two DHCP pools for VLAN 10 and VLAN 20, excludes the specified address ranges, sets the default gateway to the subinterface IP, provides DNS server 8.8.8.8, and sets the lease to 1 day. The lease command uses days as the default unit.

✗ip dhcp excluded-address 192.168.10.1 192.168.10.10 ip dhcp excluded-address 192.168.20.1 192.168.20.10 ip dhcp pool VLAN10 network 192.168.10.0 /24 default-router 192.168.10.1 dns-server 8.8.8.8 lease 1 0 0 ip dhcp pool VLAN20 network 192.168.20.0 /24 default-router 192.168.20.1 dns-server 8.8.8.8 lease 1 0 0Wrong answer — click to see why▾

Why this is wrong here

The specific factual error is that Cisco IOS DHCP pool network command does not accept CIDR prefix length; it requires a subnet mask in dotted decimal format.

Why candidates choose this

Candidates may be familiar with CIDR notation from other contexts (like ACLs or routing) and incorrectly assume it works in DHCP pool configuration.

✗ip dhcp excluded-address 192.168.10.1 192.168.10.10 ip dhcp excluded-address 192.168.20.1 192.168.20.10 ip dhcp pool VLAN10 network 192.168.10.0 255.255.255.0 default-router 192.168.10.1 dns-server 8.8.8.8 lease 24 ip dhcp pool VLAN20 network 192.168.20.0 255.255.255.0 default-router 192.168.20.1 dns-server 8.8.8.8 lease 24Wrong answer — click to see why▾

Why this is wrong here

The specific factual error is that the lease command's default unit is days, so 'lease 24' sets a lease of 24 days, not 1 day.

Why candidates choose this

Candidates might think the lease time is in hours because many other network parameters use seconds or minutes, or they may confuse it with the DHCP lease time in Windows which is in hours.

✗ip dhcp excluded-address 192.168.10.1 192.168.10.10 ip dhcp excluded-address 192.168.20.1 192.168.20.10 ip dhcp pool VLAN10 network 192.168.10.0 255.255.255.0 default-router 192.168.10.1 dns-server 8.8.8.8 lease 24 ip dhcp pool VLAN20 network 192.168.20.0 255.255.255.0 default-router 192.168.20.1 dns-server 8.8.8.8 lease 24Wrong answer — click to see why▾

Why this is wrong here

The lease command sets duration in days; `lease 24` gives a 24-day lease instead of a 1-day lease.

Why candidates choose this

Candidates might see this as correct and be confused by the duplication, but they should recognize that only one answer is correct.

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: an active trunk can still block the VLAN you need

A trunk being up does not prove every VLAN is crossing it. Check allowed VLAN lists, native VLAN mismatch, VLAN existence and access-port assignment.

Trap categories for this question

  • Command / output trap

    This is incorrect because the 'network' command in DHCP pool configuration requires a subnet mask in dotted decimal format, not CIDR notation (/24). Also, the lease command format '1 0 0' specifies days, hours, minutes; but the correct syntax for 1 day is simply 'lease 1' or 'lease 1 0 0' is acceptable, but the CIDR notation is invalid.

Detailed technical explanation

How to think about this question

VLAN questions usually combine access-port and trunking clues. The key is to identify whether the issue is local to one switchport, caused by the trunk, or caused by the VLAN not existing where it needs to exist.

KKey Concepts to Remember

  • Access ports place end devices into a single VLAN.
  • Trunk ports carry multiple VLANs between switches.
  • Allowed VLAN lists decide which VLANs can cross a trunk.
  • Native VLAN mismatch can create confusing symptoms.

TExam Day Tips

  • Use show vlan brief to verify access VLANs.
  • Use show interfaces trunk to verify trunk state and allowed VLANs.
  • Do not treat every same-VLAN issue as a routing problem.

Key takeaway

A trunk being up does not mean the VLAN is allowed across it. Always verify the allowed VLAN list and whether the VLAN exists on both switches.

Real-world example

How this comes up in practice

A help-desk technician troubleshoots why a newly connected PC cannot reach shared printers on the same floor. The cable is good, the switch port is active, but the PC is in VLAN 20 and the printers are in VLAN 10. The uplink trunk only allows VLAN 10. A trunk being up does not mean every VLAN crosses it.

What to study next

Got this wrong? Here's your next step.

Review VLAN allowed lists, native VLAN mismatch detection, and how to verify VLAN membership with show vlan brief and show interfaces trunk. Then practise related 200-301 questions on switching, trunking, and access-port configuration.

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FAQ

Questions learners often ask

What does this 200-301 question test?

Network Services and Security — This question tests Network Services and Security — Access ports place end devices into a single VLAN..

What is the correct answer to this question?

The correct answer is: ip dhcp excluded-address 192.168.10.1 192.168.10.10 ip dhcp excluded-address 192.168.20.1 192.168.20.10 ip dhcp pool VLAN10 network 192.168.10.0 255.255.255.0 default-router 192.168.10.1 dns-server 8.8.8.8 lease 1 ip dhcp pool VLAN20 network 192.168.20.0 255.255.255.0 default-router 192.168.20.1 dns-server 8.8.8.8 lease 1 — Option A correctly uses `lease 1` for a 1-day lease, dotted decimal subnet masks, and proper DHCP pool settings. Option B incorrectly uses CIDR notation `/24` in the network command, which IOS does not accept. Option C uses `lease 24`, which is interpreted as 24 days, not 1 day. Option D also incorrectly uses `lease 24`, resulting in a 24-day lease instead of the required 1-day lease.

What should I do if I get this 200-301 question wrong?

Review VLAN allowed lists, native VLAN mismatch detection, and how to verify VLAN membership with show vlan brief and show interfaces trunk. Then practise related 200-301 questions on switching, trunking, and access-port configuration.

What is the key concept behind this question?

Access ports place end devices into a single VLAN.

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Last reviewed: Jun 7, 2026

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