CCNA Network Infrastructure and Connectivity Practice Question
A junior network engineer is configuring a new Windows 10 workstation to connect to the corporate network. The network uses a /24 subnet mask and has a default gateway of 192.168.1.1. The workstation obtains its IP address automatically from a DHCP server, but the engineer needs to manually set a static IPv4 address of 192.168.1.50 and ensure the workstation can reach the internet. Which configuration step must the engineer take to satisfy these requirements?
⚠ Common exam trap
Cisco often tests the requirement that the default gateway must be on the same subnet as the host's IP address, and a common trap is to confuse the gateway address with the host's own IP or to use an incorrect subnet mask that still allows local communication but breaks routing.
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
✓
Set the subnet mask to 255.255.255.0 and the default gateway to 192.168.1.1
A /24 subnet mask (255.255.255.0) matches the network prefix of the default gateway 192.168.1.1, ensuring the workstation can route traffic to the internet via that gateway. Option A fails because a /16 mask (255.255.0.0) does not match the corporate /24 network, causing incorrect network identification and potential routing issues. Option C fails because leaving the default gateway blank means the host cannot reach any network beyond its local subnet, so internet access is impossible. Option D fails because using the host's own IP (192.168.1.50) as the default gateway would cause the host to attempt to route traffic to itself, never reaching the actual gateway.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Set the subnet mask to 255.255.0.0 and the default gateway to 192.168.1.1
Why it's wrong here
Using a /16 subnet mask (255.255.0.0) is incorrect for a /24 network. This would cause the workstation to consider a much larger range of addresses as local, leading to incorrect routing decisions and potential connectivity problems.
- ✓
Set the subnet mask to 255.255.255.0 and the default gateway to 192.168.1.1
Why this is correct
This is the correct configuration. The subnet mask 255.255.255.0 corresponds to a /24 prefix, which matches the network. The default gateway 192.168.1.1 is the router's IP on the same subnet, allowing the workstation to reach the internet.
- ✗
Set the subnet mask to 255.255.255.0 and leave the default gateway blank
Why it's wrong here
With a /24 subnet mask (255.255.255.0), the workstation knows that addresses in the range 192.168.1.1–192.168.1.254 are local and reachable via ARP, but it has no route for any destination outside that subnet. When the default gateway is left blank, the workstation's routing table contains only the connected route to 192.168.1.0/24, so any packet destined for a non-local IP address (e.g., an internet server) is considered unreachable and is dropped with an error such as 'Destination Host Unreachable' or 'No Route to Host.' Local devices on the same subnet still communicate, but the workstation cannot reach the internet, a corporate WAN, or any other VLAN, making this configuration incomplete for typical network connectivity.
- ✗
Set the subnet mask to 255.255.255.0 and the default gateway to 192.168.1.50
Why it's wrong here
Setting the default gateway to 192.168.1.50 (the workstation's own IP) is invalid. The gateway must be a different device (typically a router) on the same subnet; otherwise, the workstation would try to route traffic to itself, which fails.
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.
✓Set the subnet mask to 255.255.255.0 and the default gateway to 192.168.1.1Correct answer▾
Why this is correct
This is the correct configuration. The subnet mask 255.255.255.0 corresponds to a /24 prefix, which matches the network. The default gateway 192.168.1.1 is the router's IP on the same subnet, allowing the workstation to reach the internet.
✗Set the subnet mask to 255.255.0.0 and the default gateway to 192.168.1.1Wrong answer — click to see why▾
Why this is wrong here
Setting the subnet mask to 255.255.0.0 (/16) on a /24 network causes the workstation to consider IP addresses outside the local /24 subnet as local, leading to incorrect routing decisions. The workstation will not send traffic to the default gateway for destinations that are actually remote, resulting in connectivity failures.
Why candidates choose this
A student might confuse subnet masks and think that a larger subnet mask (like /16) is more permissive or 'better' for connectivity, not realizing that it actually disrupts proper routing by misidentifying which addresses are local.
✗Set the subnet mask to 255.255.255.0 and leave the default gateway blankWrong answer — click to see why▾
Why this is wrong here
Leaving the default gateway blank means the workstation has no route to destinations outside its own subnet. Without a default gateway, the workstation cannot send traffic to the internet or any other network beyond the local segment, even though it can communicate with devices on the same subnet.
Why candidates choose this
A student might think that a default gateway is optional or only needed for certain types of traffic, not realizing that it is essential for reaching any off-subnet destination, including internet access.
✗Set the subnet mask to 255.255.255.0 and the default gateway to 192.168.1.50Wrong answer — click to see why▾
Why this is wrong here
Setting the default gateway to the workstation's own IP address (192.168.1.50) is invalid because the gateway must be a different device, typically a router. The workstation would attempt to route traffic to itself, which fails, as no device can forward packets to itself as a gateway.
Why candidates choose this
A student might mistakenly think that the default gateway should be the same as the workstation's IP address, confusing it with the concept of a loopback address or simply not understanding that the gateway must be a separate device on the same subnet.
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
Quick reference
IPv4 Address Class Summary
| Class | First Octet Range | Default Mask | Networks | Hosts per Network |
|---|---|---|---|---|
| A | 1–126 | /8 (255.0.0.0) | 126 | 16,777,214 |
| B | 128–191 | /16 (255.255.0.0) | 16,384 | 65,534 |
| C | 192–223 | /24 (255.255.255.0) | 2,097,152 | 254 |
| D | 224–239 | N/A | Multicast groups | — |
| E | 240–255 | N/A | Reserved / experimental | — |
127.x.x.x is reserved for loopback. Modern networks use CIDR (classless) rather than classful addressing.
Go deeper
Related to this question
Learn chapter
IPv4 Addressing and Address Classes
Key term
Subnet
A subnet is a logical subdivision of an IP network, created by partitioning a larger network address space using subnet masks.
Key term
Subnet mask
A subnet mask is a 32-bit number that helps a computer or network device determine which part of an IP address identifies the network and which part identifies the host device on that network.
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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.