CCNA Network Infrastructure and Connectivity — Timed 100 Questions

Question 1

What does a host rely on when using SLAAC to build an IPv6 address?

Accepted Answer

A Router Advertisement containing the network prefix. With Stateless Address Autoconfiguration, hosts learn the prefix information from ICMPv6 Router Advertisements and then build their own interface identifier.

Answer

Only a DNS reply

Answer

An ARP reply from the default gateway

Answer

A VTP summary advertisement

Question 2

What is the primary purpose of encapsulation in networking?

Accepted Answer

To add protocol information as data moves down the stack. Encapsulation adds protocol headers and trailers so data can be interpreted and forwarded correctly at each layer.

Answer

To encrypt every frame before transmission

Answer

To remove all addressing information before forwarding

Answer

To convert unicast traffic into broadcast traffic

Question 3

Which statement best describes the purpose of an IPv6 link-local address?

Accepted Answer

It is used for communication only within the local link or network segment.. An IPv6 link-local address is meant for communication on the local network segment only. In plain language, it lets devices talk to nearby neighbors without needing a globally routable address. Routers use link-local addresses for neighbor relationships, and hosts use them for functions like Neighbor Discovery and communicating with the default gateway on the same link. These addresses are essential in IPv6 and are not just an emergency fallback.

Technically, link-local addresses usually begin with the FE80::/10 prefix and are automatically created on IPv6-enabled interfaces. They are never routed beyond the local link, which is why they are different from global unicast addresses. They do not replace the concept of a default gateway; instead, hosts often use the router’s link-local address as the next-hop target on the local segment.

Answer

It is publicly routable across the Internet.

Answer

It replaces the need for a default gateway on IPv6 hosts.

Answer

It is used only when DHCPv6 fails.

Question 4

What is the usable host range for subnet 10.1.1.192/27?

Accepted Answer

10.1.1.193 to 10.1.1.222. A /27 subnet contains 32 total addresses. In plain language, the 10.1.1.192/27 block runs from 10.1.1.192 through 10.1.1.223. The first address is the network address and the last is the broadcast address, so the usable host range is 10.1.1.193 through 10.1.1.222.

This is a common subnetting question because it checks whether you can move from subnet boundary to valid host range. The key is to identify the block correctly and then exclude the reserved first and last addresses.

Answer

10.1.1.192 to 10.1.1.223

Answer

10.1.1.194 to 10.1.1.223

Answer

10.1.1.160 to 10.1.1.191

Question 5

Which statement best describes an IPv6 link-local address?

Accepted Answer

It is used only on the local link and is not routed beyond that segment.. An IPv6 link-local address is used only on the local Layer 2 segment and is not routed beyond that link. In practical terms, it lets devices communicate with nearby neighbors even before or without having a globally routable IPv6 address. Routers use link-local addresses heavily for neighbor relationships, and hosts often use the router’s link-local address as the next hop for off-link traffic.

This is a foundational IPv6 concept. The common trap is to treat link-local addresses like normal Internet-routable addresses. They are not. They are essential, but they are local-scope only.

Answer

It is the public IPv6 address used for Internet reachability.

Answer

It is used only when DHCPv6 fails.

Answer

It replaces the need for a default gateway.

Question 6

Which statement best compares a MAC address and an IP address?

Accepted Answer

A MAC address is a local Layer 2 identifier, while an IP address is a Layer 3 logical address used across networks.. A MAC address is primarily a local Layer 2 identifier used for frame delivery on the immediate segment, while an IP address is a Layer 3 logical address used for routed communication across networks. In practical terms, switches make frame-forwarding decisions using MAC information locally, while routers forward packets based on IP information between networks.

This is one of the most fundamental distinctions in networking. The exam often tests whether you can separate local data-link identity from routed network-layer identity.

Answer

A MAC address is used only by routers, while an IP address is used only by switches.

Answer

MAC and IP addresses are interchangeable in routed networks.

Answer

IP addresses are used only inside one Ethernet broadcast domain.

Question 7

Which statement best describes a global unicast IPv6 address?

Accepted Answer

It is the normal IPv6 address type used for routed communication across networks.. A global unicast IPv6 address is the normal IPv6 address type used for routed communication across networks. In practical terms, it plays the role that a normal public unicast IPv4 address plays in routed IPv4 communication. Unlike a link-local address, it is not limited to the local segment only.

This question tests whether you can separate IPv6 address scope correctly. The common mistake is to confuse global unicast with link-local or loopback addressing.

Answer

It can be used only on the local link and is never routed.

Answer

It is used only for loopback testing inside a device.

Answer

It is created only when EUI-64 is disabled.

Question 8

Which statement best describes the relationship between a default gateway and a host’s subnet mask in IPv4?

Accepted Answer

The subnet mask determines whether a destination is local, and the default gateway is used for remote destinations.. The subnet mask helps the host decide whether a destination is local or remote, and the default gateway is used when the destination is remote. In practical terms, the mask tells the host whether it should ARP locally or send the packet toward the router. The gateway then provides the next hop for off-subnet traffic.

This is one of the most foundational host-networking relationships in IPv4.

Answer

The default gateway replaces the need for the subnet mask.

Answer

The subnet mask is used only by routers, not by hosts.

Answer

The default gateway is used only for broadcast traffic.

Question 9

Which statement best describes the purpose of Neighbor Discovery in IPv6 at a CCNA level?

Accepted Answer

It supports important local-link IPv6 functions such as neighbor discovery and local reachability behavior.. Neighbor Discovery supports key local-link IPv6 functions such as learning neighbor reachability and mapping Layer 3 information to local Layer 2 delivery. In practical terms, it helps IPv6 hosts and routers discover one another on the local segment and communicate correctly without relying on the exact same mechanisms used by IPv4.

At CCNA level, the main idea is to recognize it as a core local IPv6 function rather than a routing protocol or a wireless feature.

Answer

It is the protocol used to summarize routes between OSPF areas.

Answer

It is a wireless security standard replacing WPA3.

Answer

It is the SNMP method for polling interface counters.

Question 10

Which statement best describes why a subnet mask matters on an IPv4 host even when a default gateway is configured?

Accepted Answer

It helps the host decide whether a destination is local or must be sent to the default gateway.. The subnet mask matters because it tells the host which destinations are local and which are remote. In practical terms, the host uses the mask to decide whether it should send directly on the local link or forward toward the default gateway. Without that decision logic, the host cannot distinguish local delivery from off-subnet forwarding properly.

The default gateway does not replace the subnet mask. They work together.

Answer

It encrypts the packet before it reaches the gateway.

Answer

It chooses the wireless SSID for the host.

Answer

It automatically creates a route summarization policy.

Question 11

Which statement best explains why a host with a correct IP address but incorrect subnet mask may still fail to communicate properly?

Accepted Answer

Because the host may misidentify local versus remote destinations and choose the wrong forwarding behavior.. An incorrect subnet mask breaks the host's ability to distinguish which destinations are local and which are remote. In practical terms, the host may try to ARP for remote destinations that should have gone to the gateway, or it may send local traffic toward the router unnecessarily. That makes normal forwarding decisions unreliable even if the IP address itself looks valid.

This is why correct addressing includes both the address and the mask, not just one of them.

Answer

Because the subnet mask is used only by switches, not hosts.

Answer

Because the mask automatically provides DNS name resolution.

Answer

Because the subnet mask replaces the need for a default gateway.

Question 12

Which statement best explains why link-local IPv6 addresses are still important even when global unicast addresses are configured?

Accepted Answer

Because IPv6 still relies on link-local addressing for important local-link functions.. Link-local IPv6 addresses remain important because they are used for key on-link functions independent of wider routed addressing. In practical terms, devices use them for local neighbor relationships and other local-link behavior even when global unicast addressing is also present. They are not just a fallback; they are part of normal IPv6 operation.

This is one of the core conceptual differences between IPv4 and IPv6 host behavior.

Answer

Because global unicast addresses can be used only on serial links.

Answer

Because link-local addresses replace all static routes.

Answer

Because link-local addresses are the same thing as DNS names.

Question 13

Which statement best describes the purpose of a default gateway on a host?

Accepted Answer

It is the next hop used for traffic going to remote networks.. A default gateway provides the next hop for traffic destined to remote networks. In practical terms, when the host determines that a destination is not on its own local subnet, it sends the traffic toward the router instead of trying to deliver it directly on the local link.

This is a foundational host-networking concept and a useful easy-level question for progression.

Answer

It is the hostname of the DNS server.

Answer

It is the broadcast address for the subnet.

Answer

It is the same thing as the subnet mask.

Question 14

Which statement best describes why the subnet mask is necessary even when DNS and the default gateway are configured correctly?

Accepted Answer

Because the host still must determine local versus remote scope before deciding how to send traffic.. The subnet mask is still necessary because the host must decide whether a destination is local or remote before it knows whether to send directly or use the gateway. In practical terms, DNS may help turn names into IP addresses and the default gateway may help with remote delivery, but the host still needs its subnet logic to choose the right behavior.

This is a good medium-level foundational question because it connects several host configuration elements without confusing their roles.

Answer

Because the subnet mask is what resolves hostnames into IP addresses.

Answer

Because the subnet mask replaces the default gateway for all remote traffic.

Answer

Because the subnet mask is required only by switches, not hosts.

Question 15

Which statement best explains why a host may still fail even when the DNS server is correct, if the default gateway is wrong?

Accepted Answer

Because name resolution can succeed while remote forwarding still fails due to the wrong gateway.. A correct DNS server alone does not provide packet forwarding to remote networks. In practical terms, name resolution may succeed, but the host still needs the correct default gateway to reach destinations outside the local subnet. If the gateway is wrong, the host may know the right IP address and still fail to connect.

This is a useful host-troubleshooting reasoning question because it separates naming from forwarding.

Answer

Because DNS automatically replaces the need for any gateway.

Answer

Because a wrong gateway changes the hostname of the server.

Answer

Because hosts use the default gateway only for local traffic.

Question 16

Which statement correctly describes the purpose of ARP in an IPv4 network?

Accepted Answer

It maps an IPv4 address to a MAC address on the local segment. ARP maps a known IPv4 address to a Layer 2 MAC address on the local network segment. That allows the sender to build the Ethernet frame needed for local delivery.

Answer

It maps a MAC address to a DNS hostname

Answer

It advertises routes between routers

Answer

It negotiates trunk encapsulation between switches

Question 17

What is the purpose of the default gateway on a host?

Accepted Answer

It forwards traffic to remote networks. The default gateway is the local router interface a host uses when sending traffic to destinations outside its own subnet.

Answer

It assigns IP addresses dynamically to the host

Answer

It resolves hostnames into IP addresses

Answer

It encrypts traffic between hosts

Question 18

An interface is configured with 10.24.7.158/27. What is the broadcast address of that subnet?

Accepted Answer

10.24.7.159. A /27 uses blocks of 32 addresses. The block containing .158 is 10.24.7.128 through 10.24.7.159, so .159 is the broadcast address.

Answer

10.24.7.191

Answer

10.24.7.127

Answer

10.24.7.160

Question 19

Which two statements accurately compare TCP and UDP? (Choose two.)

Accepted Answer

TCP provides connection-oriented transport. TCP is connection-oriented and uses sequencing, acknowledgments, and related controls. UDP is simpler and has lower overhead, but it does not guarantee delivery.

Answer

UDP guarantees delivery through acknowledgments

Answer

TCP does not use port numbers

Answer

UDP is always faster because it avoids congestion

Question 20

Which medium is the most common choice for a 10G uplink between wiring closets on different floors of the same building?

Accepted Answer

Fiber optic cable. Fiber is commonly used for building uplinks because it supports higher bandwidth and longer distances than typical copper for this use case.

Answer

Rollover cable

Answer

Coaxial cable

Answer

Console cable