🎯 Master the Art of Subnetting: 30 Practice Questions & Answers for CCNA Exam
When preparing for the Cisco Certified Network Associate (CCNA) exam, one topic that consistently challenges students is subnetting. Whether you’re an aspiring network engineer, a system integrator, or a technician brushing up on fundamentals, subnetting is a must-master skill. This guide breaks down the essential theory and offers 30 carefully curated practice questions with answers—from beginner to advanced—so you can walk into your exam with confidence.
📚 Why Subnetting is Crucial in the CCNA Exam
Subnetting isn’t just a chapter in your textbook—it’s a core networking skill. Cisco exams love to test your ability to break down an IP network into smaller, logical pieces. Subnetting enables:
- Efficient IP address allocation
- Network segmentation and traffic isolation
- Optimized routing table management
- Improved performance and security
The CCNA often includes real-world subnetting scenarios. Being fast and accurate can be the difference between passing or failing.
🧠 Subnetting Basics Refresher
Before jumping into the practice questions, here’s a quick cheat sheet:
| CIDR Notation | Subnet Mask | Usable Hosts | Block Size | Broadcast Address |
|---|---|---|---|---|
| /24 | 255.255.255.0 | 254 | 256 | x.x.x.255 |
| /26 | 255.255.255.192 | 62 | 64 | x.x.x.63 |
| /28 | 255.255.255.240 | 14 | 16 | x.x.x.15 |
| /30 | 255.255.255.252 | 2 | 4 | x.x.x.3 |
📝 Subnetting Practice Questions & Answers
🔹 Beginner Level
- What is the subnet mask for /25?
🅰️ 255.255.255.128 - How many usable hosts are in a /28 network?
🅰️ 14 - What is the broadcast address for 192.168.10.64/26?
🅰️ 192.168.10.127 - What are the valid host addresses for 10.0.0.0/30?
🅰️ 10.0.0.1 – 10.0.0.2 - What is the network address for 172.16.8.66/20?
🅰️ 172.16.0.0
🔹 Intermediate Level
- Given 192.168.1.130/26, what is the first usable host?
🅰️ 192.168.1.129 - How many subnets are created with a /27 mask from a Class C network?
🅰️ 8 subnets - What is the subnet mask for 5 usable hosts?
🅰️ /29 - In a /23 subnet, how many valid host addresses exist?
🅰️ 510 - What’s the range of usable IPs in 172.16.32.0/27?
🅰️ 172.16.32.1 – 172.16.32.30
🔹 Advanced Level
- A company has been allocated 192.168.1.0/24. They need 5 subnets with at least 30 hosts each. What mask should they use?
🅰️ /27 - Calculate the subnet address of 10.10.45.66/19.
🅰️ 10.10.32.0 - What subnet does 192.168.100.200/28 belong to?
🅰️ 192.168.100.192/28 - You need to create 100 subnets. What subnet mask do you need for a Class B network?
🅰️ /25 or lower (to provide more than 100 subnets) - If you subnet a /16 into /20s, how many subnets do you get?
🅰️ 16 subnets
CCNA Subnetting: 30 Practice Questions & Answers
Question 1:
Given IP: 192.168.10.0/27. How many usable host addresses per subnet? Answer: 30
Question 2:
What is the subnet mask for the network 172.16.0.0 needing at least 500 hosts per subnet? Answer: 255.255.254.0
Question 3:
What subnet mask should you use to create 8 subnets from Class C IP address? Answer: 255.255.255.224
Question 4:
Given IP: 10.0.0.0/13. What is the total number of subnets and hosts per subnet? Answer: Subnets: 32, Hosts: 524,286
Question 5:
Which subnet mask allows 6 usable hosts per subnet? Answer: 255.255.255.248
Question 6:
What is the broadcast address of 192.168.1.0/26? Answer: 192.168.1.63
Question 7:
How many bits are borrowed to create a subnet mask of 255.255.240.0? Answer: 4 bits
Question 8:
What is the first usable IP in the subnet 172.16.32.0/19? Answer: 172.16.32.1
Question 9:
What’s the subnet mask to create exactly 4 subnets from 192.168.20.0/24? Answer: 255.255.255.192
Question 10:
Given 10.10.0.0/16, what subnet mask will allow 1000 hosts per subnet? Answer: 255.255.252.0
Question 11:
What is the subnet address for IP 192.168.5.130 with subnet mask 255.255.255.192? Answer: 192.168.5.128
Question 12:
How many usable IP addresses are there with a subnet mask of 255.255.255.240? Answer: 14
Question 13:
What is the broadcast address for subnet 172.16.0.0 with mask 255.255.192.0? Answer: 172.16.63.255
Question 14:
What mask allows for 16 subnets on a Class C IP? Answer: 255.255.255.240
Question 15:
What’s the last usable IP of subnet 192.168.50.64/27? Answer: 192.168.50.94
Question 16:
What subnet mask will provide the least waste for 200 usable hosts? Answer: 255.255.255.0
Question 17:
How many subnets can be created from IP 10.0.0.0/18? Answer: 4,096
Question 18:
What subnet mask creates exactly 2 usable hosts per subnet? Answer: 255.255.255.252
Question 19:
What is the network address for host 172.16.25.100/22? Answer: 172.16.24.0
Question 20:
Calculate the broadcast address for IP 192.168.2.60/28. Answer: 192.168.2.63
Question 21:
Given 172.30.0.0/20, what is the total number of usable host addresses? Answer: 4,094
Question 22:
What subnet mask would you use for a Class B network needing exactly 30 subnets? Answer: 255.255.248.0
Question 23:
Identify the subnet address for host 192.168.100.37/29. Answer: 192.168.100.32
Question 24:
Which subnet mask allows 254 usable hosts? Answer: 255.255.255.0
Question 25:
What is the range of usable hosts for subnet 10.1.0.0/23? Answer: 10.1.0.1 – 10.1.1.254
Question 26:
What’s the subnet mask if you borrow 5 bits in Class C? Answer: 255.255.255.248
Question 27:
What’s the subnet broadcast address of IP 192.168.1.170 with mask 255.255.255.224? Answer: 192.168.1.191
Question 28:
Given the address 10.0.15.7/25, what’s the subnet address? Answer: 10.0.15.0
Question 29:
How many hosts per subnet can you have with mask 255.255.252.0? Answer: 1,022
Question 30:
What subnet mask is needed to support 100 subnets on a Class B network? Answer: 255.255.254.0
⚙️ How to Master Subnetting Faster
Here are some proven tips used by top CCNA scorers:
- Memorize subnet values: Know the magic numbers: 256, 128, 64, 32, 16, 8, 4, 2
- Binary math is your friend: Get comfortable with powers of 2
- Use cheat sheets: Flashcards, tables, or printable subnet calculators
- Daily practice: Set a goal to solve 10–15 questions per day under time constraints
- Visualize with VLSM: Use Variable Length Subnet Masking to reinforce your understanding
🛠 Suggested Tools for Subnetting Practice
- Cisco Packet Tracer – Simulate routing and subnetting scenarios
- SubnettingPractice.com – Random quiz generators
- Subnet calculators – Great for verification after solving manually
- CCNA Prep Books – Look for practice labs that emphasize real deployment
🏁 Final Thoughts
If you want to pass your CCNA exam with confidence, subnetting must become second nature. This set of 45 focused questions offers more than just memorization—it helps you apply logic, identify patterns, and build speed. Don’t just read—practice!