CCNA Network Infrastructure and Connectivity Practice Test 9 — 15 Questions

Question 1

A network administrator is setting up a new branch office with a Cisco router acting as a DHCP server for the local LAN. The LAN uses the subnet 192.168.10.0/24. The administrator wants to exclude the first 10 addresses (192.168.10.1 through 192.168.10.10) from being assigned to DHCP clients because they are reserved for static assignments. Which command correctly accomplishes this?

Choose an answer to begin — your selection is scored in the full session.

Accepted Answer

ip dhcp excluded-address 192.168.10.1 192.168.10.10. The 'ip dhcp excluded-address' command in global configuration mode reserves a range of addresses from being assigned by DHCP. The correct syntax uses a space between the start and end addresses. This prevents the DHCP server from offering those addresses to clients, ensuring they remain available for static assignment. It is essential for avoiding IP address conflicts with infrastructure devices.

Answer

ip dhcp pool EXCLUDED
network 192.168.10.0 255.255.255.0
excluded-address 192.168.10.1 192.168.10.10

Answer

ip dhcp excluded-address 192.168.10.0 192.168.10.10

Answer

ip dhcp excluded-address 192.168.10.1-192.168.10.10

Question 2

A network engineer is implementing OSPFv2 in a multi-area topology. Area 0 is the backbone, and Area 1 is a stub area. The engineer notices that a router in Area 1 is not receiving a default route from the Area Border Router (ABR) even though the stub area is configured correctly. Which configuration on the ABR is required to inject a default route into the stub area?

Accepted Answer

area 1 stub no-summary. In a totally stubby area, the ABR blocks Type 3 summary LSAs and injects a default route into the area, reducing the size of the link-state database on internal routers. Configuring area 1 stub no-summary on the ABR accomplishes this. The default-information originate command is for ASBRs injecting external default routes, not for ABRs injecting defaults into stub areas.

Answer

redistribute static subnets

Answer

default-information originate

Answer

area 1 default-cost 1

Question 3

A network technician is troubleshooting a Cisco switch where several ports are not forwarding traffic as expected. The technician suspects a Spanning Tree Protocol (STP) issue. Which TWO statements about STP operation are accurate? (Choose two.)

Accepted Answer

STP prevents Layer 2 loops by placing redundant ports into a blocking state.. STP prevents Layer 2 loops by blocking redundant ports, and it elects a root bridge using the lowest bridge ID composed of priority and MAC address. These two facts describe the core mechanism and election process. Load balancing is not a default STP behavior, the listening state does not forward frames, and although BPDUs are used, only two answers are permitted by the stem, so the first two statements form the intended pair.

Answer

STP uses BPDUs to exchange topology information between switches.

Answer

Ports in the listening state forward data frames while learning MAC addresses.

Answer

STP load-balances traffic across all redundant links simultaneously by default.

Question 4

A network administrator is configuring a Cisco router to provide DHCP services to a LAN. The LAN uses the subnet 10.10.10.0/24. The administrator wants the router to assign IP addresses from 10.10.10.10 to 10.10.10.100, with a lease time of 1 day, and to exclude addresses 10.10.10.50 to 10.10.10.60 for static assignments. Which configuration sequence on the router accomplishes this?

Accepted Answer

ip dhcp excluded-address 10.10.10.1 10.10.10.9; ip dhcp excluded-address 10.10.10.101 10.10.10.254; ip dhcp excluded-address 10.10.10.50 10.10.10.60; ip dhcp pool LAN; network 10.10.10.0 255.255.255.0; lease 1. The correct configuration uses multiple ip dhcp excluded-address commands to exclude addresses outside the desired dynamic range and the static range. The network command defines the subnet, and lease 1 sets a 1-day lease. This leaves the desired addresses available for DHCP clients.

Answer

ip dhcp excluded-address 10.10.10.50 10.10.10.60; ip dhcp pool LAN; network 10.10.10.0 255.255.255.0; range 10.10.10.10 10.10.10.100; lease 1

Answer

ip dhcp excluded-address 10.10.10.50 10.10.10.60; ip dhcp pool LAN; network 10.10.10.0 255.255.255.0; default-router 10.10.10.1; lease 1

Answer

ip dhcp pool LAN; network 10.10.10.0 255.255.255.0; ip dhcp excluded-address 10.10.10.50 10.10.10.60; range 10.10.10.10 10.10.10.100; lease 1

Question 5

A network technician is troubleshooting a routing issue on a Cisco router. The router has two static routes to the same destination network: one with a next-hop IP address and one with an exit interface. The technician notices that the route with the next-hop IP address is installed in the routing table, but the route with the exit interface is not. What is the most likely reason for this behavior?

Accepted Answer

The exit-interface route requires a recursive lookup that fails because the destination is not directly connected.. Static routes can be configured with a next-hop IP address, an exit interface, or both. A route with only an exit interface on a multi-access network like Ethernet is treated as directly connected and may not be installed if the router cannot resolve the next-hop MAC address for all destinations. The recommended practice is to use a next-hop IP address or both. The next-hop route is installed because it provides a resolvable next hop.

Answer

The exit interface is down, so the route is not installed.

Answer

The route with the exit interface has a higher administrative distance than the next-hop route.

Answer

The next-hop IP address is unreachable, causing the exit-interface route to be removed.

Question 6

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 7

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 8

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

Question 9

At which OSI layer do routers make forwarding decisions based on logical addressing?

Accepted Answer

Layer 3. Routers operate at the network layer when making forwarding decisions based on logical Layer 3 addresses such as IPv4 or IPv6 destination addresses.

Answer

Layer 1

Answer

Layer 2

Answer

Layer 4

Question 10

Which command enables IPv6 routing on a Cisco router?

Accepted Answer

ipv6 unicast-routing. The global configuration command 'ipv6 unicast-routing' enables IPv6 forwarding on a Cisco router. 'ipv6 enable' is an interface-level command used to enable IPv6 on a specific interface, not globally. 'ip routing ipv6' and 'ipv6 route enable' are syntactically invalid commands that do not exist in Cisco IOS.

Answer

ipv6 enable

Answer

ip routing ipv6

Answer

ipv6 route enable

Question 11

A host sends traffic to a web server on another subnet. Which address is used as the destination MAC address in the first Ethernet frame sent by the host?

Accepted Answer

The MAC address of the local default gateway. When a host wants to communicate with a device on a different subnet, it cannot reach that device directly. The host must send the frame to its default gateway, which is the router that connects to other subnets. Therefore, the destination MAC address in the first Ethernet frame is the MAC address of the local default gateway, not the remote web server (A). The DNS server (C) is used for name resolution, not for forwarding traffic. The broadcast MAC address (D) would send the frame to all devices on the local subnet, which is not appropriate for unicast communication to a remote destination.

Answer

The MAC address of the remote web server

Answer

The MAC address of the DNS server

Answer

The broadcast MAC address

Question 12

A branch office needs four subnets from the 192.168.50.0/24 network, with each subnet supporting up to 50 hosts. Which prefix length should be used for each subnet?

Accepted Answer

/26. Each subnet must support at least 50 hosts, so /26 is the smallest suitable prefix because it provides 62 usable addresses. A /24 can be split into exactly four /26 subnets.

Answer

/25

Answer

/27

Answer

/28

Question 13

A host sends an IPv4 packet larger than the outgoing interface MTU, and the DF bit is not set. What will a router normally do?

Accepted Answer

Fragment the packet before forwarding. If fragmentation is allowed, an IPv4 router can fragment a packet to fit the outgoing interface MTU. If DF were set, the router would instead drop the packet and typically send an ICMP message back to the source.

Answer

Drop the packet without notification

Answer

Convert the packet into UDP

Answer

Forward it unchanged and let the switch fragment it

Question 14

Which IPv6 address type is automatically created on an interface and used for communication on the local link only?

Accepted Answer

Link-local. Every IPv6-enabled interface generates a link-local address, typically in the FE80::/10 range. It is used for neighbor discovery, local communication, and next-hop resolution on the same link.

Answer

Global unicast

Answer

Unique local

Answer

Multicast

Question 15

A switch port and a host NIC have a duplex mismatch. Which symptom is most likely?

Accepted Answer

Increased late collisions and poor performance. A duplex mismatch often causes collisions, frame errors, and degraded throughput, especially on the half-duplex side. It is a classic physical/link layer performance problem.

Answer

Incorrect VLAN tagging on trunks

Answer

OSPF area mismatch errors

Answer

A change in the subnet mask on the host