N10-009 Practice Test 25 — 15 Questions

Question 1

Which of the following describes a unicast transmission?

Accepted Answer

One-to-one communication. Unicast transmission is defined as one-to-one communication where a single source sends data to a single destination. In IPv4 networking, this is the standard method for most client-server interactions, such as a host sending an HTTP request to a web server. The destination MAC address in the Ethernet frame is the unique address of the target device, ensuring only that device processes the frame.

Answer

One-to-many communication

Answer

One-to-all communication

Answer

Many-to-many communication

Question 2

A network engineer is troubleshooting intermittent packet loss on a 10 km single-mode fiber link between two buildings. The link lights are on, but the interface shows a high number of CRC errors. The engineer has cleaned the fiber connectors and replaced the patch cables. What should the engineer check NEXT?

Accepted Answer

Check the transmit/receive optical power levels. CRC errors on a single-mode fiber link typically indicate physical-layer issues such as excessive attenuation or dispersion. Since cleaning connectors and replacing patch cables did not resolve the problem, the next logical step is to measure the optical power levels at both the transmitter and receiver using an optical power meter. This will confirm whether the received signal is within the acceptable range (e.g., -3 dBm to -20 dBm for 10GBASE-LR) and identify if a damaged transceiver or a splice loss is causing the errors.

Answer

Check the duplex settings on both ends

Answer

Verify the cable length is within specifications

Answer

Adjust the Spanning Tree Protocol priority

Question 3

A network engineer is designing a subnet to accommodate 50 devices in a single broadcast domain. The engineer uses a /26 subnet mask. How many usable host addresses are available?

Accepted Answer

62. A /26 subnet mask provides 2^(32-26) = 64 total addresses. Subtracting the network and broadcast addresses leaves 62 usable host addresses. This is sufficient for 50 devices in a single broadcast domain.

Answer

30

Answer

126

Answer

254

Question 4

A network administrator wants to ensure that SNMP traffic between the network monitoring server and managed devices is encrypted and provides authentication of the data origin. Which version of SNMP should be implemented?

Accepted Answer

C: SNMPv3. SNMPv3 is the correct choice because it provides both encryption (via the AuthPriv security level) and data origin authentication (via the AuthNoPriv or AuthPriv levels). Unlike earlier versions, SNMPv3 includes a security model that ensures confidentiality, integrity, and authentication, meeting the administrator's requirements.

Answer

A: SNMPv1

Answer

B: SNMPv2c

Answer

D: SNMPv2

Question 5

Which of the following network protocols operates at the Transport layer of the OSI model and provides connection-oriented, reliable data delivery?

Accepted Answer

TCP. TCP (Transmission Control Protocol) operates at the Transport layer (Layer 4) of the OSI model and provides connection-oriented, reliable data delivery through mechanisms such as three-way handshake, sequence numbers, acknowledgments, and retransmission of lost segments. This ensures that data is delivered in order and without errors, making TCP the correct choice for the question.

Answer

UDP

Answer

IP

Answer

ARP

Question 6

A user reports that they cannot access the internet. The network technician checks the workstation's IP configuration and finds the IP address 169.254.15.77. What does this address indicate?

Accepted Answer

The DHCP server is unreachable.. The IP address 169.254.15.77 falls within the Automatic Private IP Addressing (APIPA) range (169.254.0.0/16, per RFC 3927). This address is automatically assigned by the operating system when a DHCP client fails to receive a lease from a DHCP server, indicating that the DHCP server is unreachable or not responding.

Answer

The workstation has a static IP address configured.

Answer

The DNS server is down.

Answer

The default gateway is misconfigured.

Question 7

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 8

A network technician needs to capture and analyze packets on a specific network segment to identify the source of a performance slowdown. Which tool is best suited for this task?

Accepted Answer

Protocol analyzer (e.g., Wireshark). A protocol analyzer like Wireshark is the correct tool because it captures and decodes packets at the data-link layer, allowing the technician to inspect frame headers, IP addresses, TCP/UDP ports, and payload contents on a specific network segment. This deep packet inspection is essential for identifying the root cause of performance slowdowns, such as excessive retransmissions, high latency, or application-layer issues. Unlike other tools, a protocol analyzer provides granular visibility into traffic patterns and protocol behavior.

Answer

Port scanner (e.g., Nmap)

Answer

Ping

Answer

Traceroute

Question 9

A network administrator is investigating reports of slow network performance. Which tool should the administrator use to capture and analyze individual packets to identify the cause of the latency?

Accepted Answer

Packet analyzer. A packet analyzer captures and decodes individual packets, allowing the administrator to inspect frame-level details, identify retransmissions, TCP window scaling issues, or application-layer delays that cause latency. This granularity is essential for pinpointing the exact cause of slow performance.

Answer

Throughput tester

Answer

Spectrum analyzer

Answer

NetFlow analyzer

Question 10

A network administrator plans to make a configuration change on a core switch during a maintenance window. According to best practices, which document should the administrator prepare and have approved before making the change?

Accepted Answer

A) Change management request. A change management request is the correct document because it formalizes the proposed configuration change, including the scope, risk assessment, rollback plan, and approval chain. This ensures that all stakeholders review and authorize the change before implementation, reducing the risk of unintended network outages or security gaps. Best practices from ITIL and Cisco's own change management guidelines mandate this process for any production network device modification.

Answer

B) Network diagram

Answer

C) Incident report

Answer

D) Backup configuration

Question 11

Which of the following best describes the primary difference between a hub and a switch?

Accepted Answer

A hub broadcasts all frames to all ports; a switch forwards frames only to the destination port. A hub operates at Layer 1 (physical layer) and simply repeats electrical signals out all ports, causing all connected devices to receive every frame. A switch operates at Layer 2 (data link layer) and uses the MAC address table to forward frames only to the specific port where the destination device resides, reducing unnecessary traffic and improving network efficiency.

Answer

A switch is faster than a hub because it operates at Layer 3

Answer

A hub can segment collision domains; a switch cannot

Answer

Both hubs and switches operate at the same OSI layer but use different frame types

Question 12

A network administrator wants to implement a protocol to automatically assign IP addresses to devices on the network. Which of the following protocols is used for this purpose?

Accepted Answer

DHCP. DHCP (Dynamic Host Configuration Protocol) is the correct answer because it is specifically designed to automatically assign IP addresses and other network configuration parameters (such as subnet mask, default gateway, and DNS servers) to devices on a network. This eliminates the need for manual IP configuration, reducing administrative overhead and preventing address conflicts.

Answer

DNS

Answer

ARP

Answer

ICMP

Question 13

A network administrator wants to prevent unauthorized devices from connecting to the network by limiting the number of MAC addresses allowed on a switch port. Which security feature should be configured?

Accepted Answer

Port security. Port security is the correct feature because it directly restricts the number of unique MAC addresses that can be learned on a switch port, preventing unauthorized devices from connecting. When the configured limit is exceeded, the switch can take actions such as shutdown, restrict, or protect, effectively blocking the unauthorized device. This is a Layer 2 access control mechanism that operates on the switch port itself.

Answer

802.1X

Answer

DHCP snooping

Answer

Dynamic ARP inspection

Question 14

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 15

An OSPF network uses a multi-access segment with four routers. All router interfaces have the default OSPF priority of 1. Which router becomes the Designated Router (DR)?

Accepted Answer

The router with the highest router ID. In an OSPF multi-access network, the Designated Router (DR) is elected based on the highest OSPF priority value, with a tie-breaking mechanism using the highest Router ID. Since all routers have the default priority of 1, the router with the highest Router ID wins the DR election. This ensures a stable topology for reducing LSA flooding and adjacency overhead.

Answer

The router with the lowest IP address on the segment

Answer

The router with the highest bandwidth on the connecting interface

Answer

The router with the oldest uptime