N10-009 Networking Concepts Practice Test 2 — 15 Questions

Question 1

A network engineer needs to assign IP addresses to a new subnet that will support exactly 25 devices. Which subnet mask would provide the minimum number of usable host addresses while still accommodating the requirement?

Accepted Answer

255.255.255.224 (/27). Option B (255.255.255.224, /27) provides 32 total addresses per subnet, with 30 usable host addresses (2^(32-27)-2 = 30). This is the smallest subnet that can accommodate exactly 25 devices, as /28 yields only 14 usable hosts and /26 yields 62, which is excessive.

Answer

255.255.255.240 (/28)

Answer

255.255.255.192 (/26)

Answer

255.255.255.128 (/25)

Question 2

A network engineer is designing a network and needs to ensure that broadcast traffic is contained within a single broadcast domain. Which of the following devices should be used to create these separate broadcast domains?

Accepted Answer

Router. A router operates at Layer 3 of the OSI model and does not forward broadcast frames by default, making it the correct device to segment a network into separate broadcast domains. Each interface on a router creates a distinct broadcast domain, ensuring that broadcast traffic is contained within that interface's subnet.

Answer

Hub

Answer

Bridge

Answer

Switch

Question 3

A network administrator wants to segment the network into multiple virtual LANs to reduce broadcast traffic. Which device is required to route traffic between these VLANs?

Accepted Answer

Router or Layer 3 switch. VLANs operate at Layer 2, isolating broadcast domains. To route traffic between different VLANs, a device that can forward packets based on Layer 3 IP addresses is required. A router or a Layer 3 switch (which performs hardware-based routing using ASICs) provides the necessary inter-VLAN routing functionality.

Answer

Layer 2 switch

Answer

Bridge

Answer

Hub

Question 4

A company needs a subnet that will support exactly 50 devices. Which subnet mask provides the minimum number of usable host addresses while still accommodating the requirement?

Accepted Answer

255.255.255.192 (/26). Option B (255.255.255.192, /26) provides 2^(32-26) - 2 = 62 usable host addresses, which is the smallest subnet that supports exactly 50 devices. A /27 yields only 30 usable addresses (too few), while a /25 yields 126 usable addresses (wasteful). The requirement is to minimize waste while meeting the need.

Answer

255.255.255.128 (/25)

Answer

255.255.255.224 (/27)

Answer

255.255.255.240 (/28)

Question 5

A network administrator is configuring BGP between two autonomous systems. Which BGP attribute is primarily used to influence inbound traffic to a particular AS?

Accepted Answer

MED (Multi-Exit Discriminator). The Multi-Exit Discriminator (MED) is a BGP attribute used to influence inbound traffic from a neighboring AS when multiple entry points exist. A lower MED value is preferred, allowing an AS to advertise to its neighbor which path should be used to reach it, thereby influencing traffic entering the local AS.

Answer

AS_PATH

Answer

Next Hop

Answer

Local Preference

Question 6

A technician needs to connect two different networks and forward traffic based on IP addresses. Which of the following devices operates at Layer 3 of the OSI model and should be used?

Accepted Answer

Router. A router operates at Layer 3 (Network layer) of the OSI model and makes forwarding decisions based on IP addresses. It uses routing tables and protocols such as OSPF or BGP to determine the best path for packets between different networks. This makes it the correct device for connecting two distinct networks and forwarding traffic by IP address.

Answer

Hub

Answer

Switch

Answer

Bridge

Question 7

A network administrator needs to create a subnet that supports exactly 50 hosts. Which subnet mask provides the smallest subnet that meets this requirement?

Accepted Answer

B. Option B is correct because a /26 subnet mask (255.255.255.192) provides 62 usable host addresses (2^(32-26) - 2 = 64 - 2 = 62), which is the smallest subnet that supports at least 50 hosts. A /27 would only provide 30 usable addresses, which is insufficient.

Answer

A

Answer

C

Answer

D

Question 8

A network engineer configures OSPF on two routers with a primary link (1 Gbps) and a backup link (100 Mbps). The engineer expects traffic to always use the primary link unless it fails, but the router is sending traffic over the backup link. What is the most likely cause?

Accepted Answer

B. OSPF uses cost to determine the best path, calculated as 10^8 / interface bandwidth. A 1 Gbps link has a cost of 1 (100,000,000 / 1,000,000,000), while a 100 Mbps link has a cost of 1 (100,000,000 / 100,000,000). Since both costs are equal, OSPF will load-balance traffic across both links instead of preferring the primary link, which is why traffic is seen on the backup link.

Answer

A

Answer

C

Answer

D

Question 9

A network engineer is troubleshooting connectivity issues between two data center switches that are configured to support jumbo frames with an MTU of 9000. The link is a 10 Gigabit Ethernet fiber connection. Large file transfers fail, but small transfers succeed. What is the most likely cause?

Accepted Answer

C. The most likely cause is that the MTU mismatch is causing large frames to be dropped. Jumbo frames of 9000 bytes require a consistent MTU across the entire Layer 2 path. If one switch is configured for 9000 and the other for the standard 1500, large frames will be silently discarded because the receiving switch cannot reassemble them. Small transfers succeed because they fit within the standard MTU.

Answer

A

Answer

B

Answer

D

Question 10

Which of the following best describes the function of a default gateway?

Accepted Answer

It routes packets from a local subnet to destinations on other networks.. The default gateway is a router or Layer 3 device on a local subnet that serves as the next-hop IP address for packets destined to networks outside the local subnet. When a host determines that the destination IP is not on the same subnet (using its subnet mask), it forwards the packet to the default gateway's MAC address via ARP, which then routes the packet toward the remote network. Without a correctly configured default gateway, a host can only communicate within its own subnet.

Answer

It translates private IP addresses to public IP addresses.

Answer

It provides DHCP services to clients.

Answer

It performs DNS resolution for network clients.

Question 11

A network switch is experiencing a high number of collisions on a specific port. The connected device is configured for half-duplex. Which of the following is the most likely cause?

Accepted Answer

The switch port is configured for full-duplex. When a switch port is configured for full-duplex but the connected device operates in half-duplex, a duplex mismatch occurs. The switch transmits without checking for collisions (as full-duplex does not use CSMA/CD), while the half-duplex device expects to sense the carrier before sending, leading to collisions on the port. This is the most common cause of excessive collisions on a single switch port.

Answer

The cable length exceeds 100 meters

Answer

The device is using an incorrect VLAN

Answer

The switch port is configured for 1000BASE-T but the device only supports 100BASE-TX

Question 12

A router has two routes to the same destination network: one learned via OSPF with a metric of 10, and another learned via EIGRP with a composite metric of 3072. The default administrative distances are OSPF=110, EIGRP=90. Which route will be installed in the routing table?

Accepted Answer

The EIGRP route because it has a lower administrative distance. The EIGRP route is installed because administrative distance (AD) is the primary tiebreaker when multiple routing protocols provide routes to the same destination. EIGRP has a default AD of 90, which is lower than OSPF's AD of 110, so the router prefers the EIGRP route regardless of metric values. Metrics are only compared when routes come from the same protocol.

Answer

The OSPF route because it has a lower metric

Answer

Both routes will be installed for load balancing

Answer

The OSPF route because it is a link-state protocol

Question 13

A network engineer wants to segment a LAN into multiple broadcast domains without purchasing additional hardware. Which of the following technologies should be implemented?

Accepted Answer

VLANs. VLANs (Virtual Local Area Networks) allow a network engineer to logically segment a single physical LAN switch into multiple isolated broadcast domains without purchasing additional hardware. By assigning switch ports to different VLAN IDs, broadcast traffic is confined to ports within the same VLAN, effectively creating separate Layer 2 networks on the same switch infrastructure.

Answer

Subnetting

Answer

VPN

Answer

NAT

Question 14

A network administrator needs to ensure that data sent from a host arrives at the correct destination on a different network. Which of the following provides the logical address used for this purpose in IPv4?

Accepted Answer

IP address. In IPv4, the logical address used to route data between different networks is the IP address. The IP address contains a network portion that routers use to forward packets across network boundaries, ensuring the data reaches the correct destination network and host.

Answer

MAC address

Answer

Port number

Answer

Default gateway

Question 15

A network technician is configuring a small office network with two subnets: 10.0.1.0/24 and 10.0.2.0/24. Each subnet has its own switch, and both switches are connected to a router with interfaces 10.0.1.1 and 10.0.2.1. Hosts on subnet A can ping the router's interface in their subnet but cannot ping hosts on subnet B. Which of the following is the most likely cause?

Accepted Answer

IP routing is disabled on the router.. The hosts on subnet A can ping their default gateway (10.0.1.1) but cannot reach hosts on subnet B, which indicates that the router is not forwarding packets between the two directly connected subnets. This behavior is characteristic of a router with IP routing disabled, as the router will not perform inter-VLAN or inter-subnet forwarding unless the 'ip routing' command is enabled globally. Without IP routing, the router acts as a host and will only respond to traffic destined for its own interfaces, dropping any packets that require forwarding to another subnet.

Answer

The router is not configured with a routing protocol.

Answer

The hosts in subnet A have the wrong default gateway.

Answer

The switch in subnet A is blocking ICMP traffic.