Quick Answer
The answer is 2 usable IP addresses. A /30 subnet, which corresponds to the subnet mask 255.255.255.252, provides a total of 4 IPv4 addresses, but the first address is reserved as the network identifier and the last as the broadcast address, leaving exactly two addresses available for host devices. This configuration is standard for point-to-point WAN links, like the one described in the CompTIA A+ Core 1 220-1201 exam, where conserving public IPs is critical. On the exam, this concept often appears in scenarios where a technician must determine how many devices can be assigned an IP on a serial link, and the common trap is forgetting to subtract the network and broadcast addresses from the total. A quick memory tip: for a /30, think “30 minus 2 equals 28, but only 2 hosts”—or simply remember that a /30 is the “point-to-point” subnet, giving you just two usable addresses for the two ends of the link.
This 220-1201 practice question tests your understanding of ip addressing. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. 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.
A technician is configuring a new router for a branch office. The ISP provides a public IP of 203.0.113.10/30 for the WAN interface. How many usable IP addresses does the technician have for devices on the WAN link?
2
Correct. A /30 subnet has 2 usable addresses, typically used for the two ends of a point-to-point link.
4
Why wrong: Incorrect. 4 is the total number of addresses in the subnet, but 2 are reserved for network and broadcast.
6
Why wrong: Incorrect. A /29 subnet provides 6 usable addresses, but the question specifies a /30.
1
Why wrong: Incorrect. A /30 provides 2 usable addresses, not 1.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
2
A /30 subnet mask (255.255.255.252) provides 4 total addresses: one network, one broadcast, and two usable. This is commonly used for point-to-point WAN links to conserve public IPs.
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
For each option: why learners choose it and why it is or isn't the right answer here.
2
Why this is correct
Correct. A /30 subnet has 2 usable addresses, typically used for the two ends of a point-to-point link.
Related concept
CIDR notation defines the prefix length.
4
Why it's wrong here
Incorrect. 4 is the total number of addresses in the subnet, but 2 are reserved for network and broadcast.
6
Why it's wrong here
Incorrect. A /29 subnet provides 6 usable addresses, but the question specifies a /30.
1
Why it's wrong here
Incorrect. A /30 provides 2 usable addresses, not 1.
Common exam traps
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
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.
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
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.
What to study next
Review block sizes, usable host formulas (2^n − 2), and how to find network and broadcast addresses for /24 through /30. Then practise related 220-1201 subnetting questions on CIDR, address ranges, and subnet selection.
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FAQ
IP Addressing — This question tests IP Addressing — CIDR notation defines the prefix length..
The correct answer is: 2 — A /30 subnet mask (255.255.255.252) provides 4 total addresses: one network, one broadcast, and two usable. This is commonly used for point-to-point WAN links to conserve public IPs.
Review block sizes, usable host formulas (2^n − 2), and how to find network and broadcast addresses for /24 through /30. Then practise related 220-1201 subnetting questions on CIDR, address ranges, and subnet selection.
CIDR notation defines the prefix length.
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Last reviewed: Jun 18, 2026
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