CCNA Network Infrastructure and Connectivity Practice Question

Answer analysis

Option-by-option breakdown

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

• ✗

  198.51.100.0/24

  Why it's wrong here

  198.51.100.0/24 is not a private address under RFC 1918; it belongs to the TEST-NET-2 documentation range (198.51.100.0 – 198.51.100.255) defined in RFC 5737. These addresses are reserved for use in documentation, example code, and troubleshooting guides, and while they can technically be routed, they are not intended for production private networks. Since the company needs actual private addressing for its operational network, this range fails the requirement.

  When this WOULD be correct

  If the question asked for an IP range that is suitable for documentation or examples in network design, then 198.51.100.0/24 would be correct, as it is specifically designated for such purposes.

• ✓

  172.20.0.0/16

  Why this is correct

  172.20.0.0/16 is correct because it resides inside the RFC 1918 private block 172.16.0.0/12 (172.16.0.0 – 172.31.255.255). As a private address, it is not globally routable on the internet but is fully routable within an enterprise network, making it ideal for internal IPv4 design. The /16 prefix provides 65,534 usable host addresses, which is suitable for a large company's scalable internal infrastructure.

• ✗

  169.254.0.0/16

  Why it's wrong here

  169.254.0.0/16 is the IPv4 link-local block used for Automatic Private IP Addressing (APIPA) on a single link, with no routing beyond that local segment. Addresses in this range are always configured automatically when a host fails to obtain a DHCP lease, and routers will not forward packets destined to this space. Therefore, it cannot be used for routable private addressing across a company network, even though it is considered 'private' in the sense of being non-globally routable.

  When this WOULD be correct

  In a question asking for a range suitable for automatic IP address assignment in a local network without a DHCP server, 169.254.0.0/16 would be the correct answer. This scenario would focus on local connectivity rather than internal routing.

• ✗

  224.0.0.0/4

  Why it's wrong here

  224.0.0.0/4 (224.0.0.0 – 239.255.255.255) is the multicast address space, not unicast private addressing. Multicast addresses are used for one-to-many communication, such as routing protocols (OSPF, EIGRP) or streaming, and are not routable as ordinary unicast traffic. Even though multicast packets can traverse a network, this range is fundamentally ineligible for assigning to interfaces as a source or destination unicast IPv4 address, so it fails the requirement for private IPv4 addressing.

  When this WOULD be correct

  In a question asking for the range of IP addresses designated for multicast traffic within a private network, option D would be correct. For example, if the question specified the need for a range that supports multicast applications internally without public routing, then this option would be valid.

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.

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?”

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