CCNA Network Infrastructure and Connectivity Practice Question
Which TWO statements correctly describe the configuration and verification of IPv4 and IPv6 parameters for host connectivity?
⚠ Common exam trap
Cisco often tests the misconception that a default gateway can be any routable address, but the trap here is that both IPv4 and IPv6 default gateways must be on the same local subnet as the host for Layer 2 reachability.
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
✓
On a Windows host, the default gateway IPv4 address must be on the same subnet as the host's IPv4 address.
For a host to reach outside its subnet, the default gateway's IP must be in the same subnet; otherwise the host cannot ARP for the gateway's MAC and traffic will fail. Option D is correct because DNS server addresses can be set manually or assigned via DHCP. Option B is wrong because IPv6 gateways must be on the same local link, not any global unicast address on the internet. Option C is wrong because the subnet mask defines the network/subnet portion of an IPv4 address, not the host portion. Option E is wrong because DNS is used for name resolution; local IP communication on the same subnet works without DNS.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
On a Windows host, the default gateway IPv4 address must be on the same subnet as the host's IPv4 address.
Why this is correct
On a Windows host, and on any IPv4 host, the default gateway address must reside on the same subnet as the host's own IPv4 address because the host must deliver Ethernet frames directly to the gateway using its MAC address, obtained via ARP. If the gateway were on a different subnet, the host would need to use another router to reach it, which contradicts the purpose of the default gateway as the immediate next hop. The host validates this by applying its own subnet mask to the gateway address and will reject it if it ends up in a different network.
- ✗
The IPv6 default gateway can be any global unicast address on the internet.
Why it's wrong here
In IPv6, the default gateway must be on the same link as the host; it is usually the router's link-local address (fe80::/10) discovered through Router Advertisement messages. A global unicast address from anywhere on the internet is not directly reachable at Layer 2, so the host would have no way to forward packets to it without already having a route to that remote address. Since the gateway is the literal next hop for off-link traffic, that next hop must be directly connected to the host's local link.
- ✗
The subnet mask is used to define the host portion of an IPv4 address.
Why it's wrong here
The subnet mask is a 32-bit value that separates an IPv4 address into network and host portions by using contiguous 1s to mask the network bits and 0s for the host bits. Its primary function is to define the boundary between these two parts, not to 'define' the host portion in isolation. The host portion is simply the bits left over after the mask removes the network prefix; saying the mask defines the host portion is misleading because it only delineates how many bits are available for host addressing within a subnet.
- ✓
A DNS server address can be statically configured on a host or obtained dynamically via DHCP.
Why this is correct
A host's DNS server address can be configured in two primary ways: statically typed into the TCP/IP settings of the network interface, or dynamically assigned by a DHCP server using DHCP option 6. This flexibility is essential because different networks have different DNS infrastructure, and hosts may need to switch name servers as they move between networks. Static configuration provides a fixed, predictable server, while DHCP simplifies administration by automatically distributing the correct DNS addresses along with IP, mask, and gateway, ensuring hosts can resolve names without manual intervention.
- ✗
Configuring a DNS server is mandatory for a host to communicate with any other device on the same subnet.
Why it's wrong here
DNS is required for name resolution, not for basic IP connectivity; devices on the same subnet can communicate purely with IP addresses and ARP, which resolves IP-to-MAC mappings without any DNS involvement. Even across subnets, routers forward packets based on destination IP addresses, and the destination host can be reached using its numeric address alone. The claim that DNS is mandatory for same-subnet communication is false because a host can always use an IP address directly, bypassing DNS entirely for data exchange.
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.
✓On a Windows host, the default gateway IPv4 address must be on the same subnet as the host's IPv4 address.Correct answer▾
Why this is correct
On a Windows host, and on any IPv4 host, the default gateway address must reside on the same subnet as the host's own IPv4 address because the host must deliver Ethernet frames directly to the gateway using its MAC address, obtained via ARP. If the gateway were on a different subnet, the host would need to use another router to reach it, which contradicts the purpose of the default gateway as the immediate next hop. The host validates this by applying its own subnet mask to the gateway address and will reject it if it ends up in a different network.
✗The IPv6 default gateway can be any global unicast address on the internet.Wrong answer — click to see why▾
Why this is wrong here
The IPv6 default gateway must be on the same link as the host, typically using the router's link-local address (fe80::/10). A global unicast address on the internet is not directly reachable without routing, so it cannot serve as a default gateway.
Why candidates choose this
Students may confuse IPv6's large address space with the idea that any global unicast address could be used as a gateway, but they overlook that the gateway must be directly connected to the host's link.
✗The subnet mask is used to define the host portion of an IPv4 address.Wrong answer — click to see why▾
Why this is wrong here
The subnet mask actually defines the network/subnet portion of an IPv4 address; the host portion is the remaining bits not covered by the mask.
Why candidates choose this
The phrase 'determines the host portion' is ambiguous; students might think the mask directly sets the host bits, but it actually separates the address into network and host parts.
✗Configuring a DNS server is mandatory for a host to communicate with any other device on the same subnet.Wrong answer — click to see why▾
Why this is wrong here
DNS is used for name resolution, not for basic IP connectivity. Hosts can communicate with other devices on the same subnet using IP addresses directly without DNS. DNS is only necessary when using hostnames instead of IP addresses.
Why candidates choose this
Students may think DNS is essential for all network communication because many applications rely on domain names, but they forget that direct IP communication does not require DNS.
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
IPv4
IPv4 is the fourth version of the Internet Protocol, a set of rules that assigns unique numerical addresses to devices so they can communicate over networks like the internet.
Key term
Name Server
A name server is a specialized server that translates human-readable domain names into machine-readable IP addresses so that computers can find each other on a 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.