100-150 Practice Test 3 — 25 Questions

Question 1

What is the primary function of the Address Resolution Protocol (ARP) in an IPv4 network?

Accepted Answer

It maps a known IPv4 address to a corresponding MAC address.. ARP (Address Resolution Protocol) is used when a host knows the IPv4 address of a destination on the same local network but needs the corresponding MAC address to build the Layer 2 frame. The host broadcasts an ARP request asking 'Who has IP X? Tell MAC Y,' and the owner of that IP replies with its MAC address. This mapping is then cached in the ARP table for future use.

Answer

It maps a known MAC address to a dynamically assigned IP address.

Answer

It translates human-readable domain names into numerical IP addresses.

Answer

It provides a secure encrypted tunnel for data transmission between hosts.

Question 2

Which device is primarily responsible for managing traffic between different IP subnets in a corporate network?

Accepted Answer

Router. A router operates at Layer 3 (Network layer) and is responsible for forwarding packets between different IP subnets by examining IP addresses and making routing decisions. It maintains a routing table and uses protocols like OSPF or BGP to determine the best path. This makes it the primary device for inter-subnet traffic management in a corporate network.

Answer

Layer 2 Switch

Answer

Hub

Answer

Repeater

Question 3

A network administrator needs to prevent unauthorized devices from connecting to a switch port while ensuring that only a specific workstation can access the network. Which security feature should be implemented?

Accepted Answer

Port Security. Port security limits the number of valid MAC addresses allowed on a port and binds a specific MAC address to a physical interface. This prevents unauthorized devices from spoofing addresses or connecting rogue hardware to the enterprise network. Implementing this feature is a fundamental step in securing the access layer against layer 2 attacks like MAC flooding or unauthorized device insertion, ensuring only authenticated hardware gains link connectivity.

Answer

DHCP Snooping

Answer

Dynamic ARP Inspection

Answer

VLAN Trunking Protocol

Question 4

An office uses Power over Ethernet (PoE) to provide power to IP phones. Which device is responsible for acting as the Power Sourcing Equipment (PSE) in this scenario?

Accepted Answer

The PoE-capable Switch. In a PoE environment, the Power Sourcing Equipment (PSE) is the device that injects power into the Ethernet cable. Usually, this is a PoE-capable switch. Understanding the roles of PSE and Powered Devices (PD) is vital for troubleshooting power-related issues at the network edge where endpoints are connected.

Answer

The IP Phone

Answer

The DHCP Server

Answer

The Patch Panel

Question 5

A network administrator is documenting the IPv6 addressing scheme for a new campus. The administrator must identify which statements about IPv6 address structure and notation are accurate. (Choose two.)

Accepted Answer

Leading zeros within each 16-bit group of an IPv6 address can be omitted to shorten the notation.. IPv6 text representation permits two key shortcuts: suppressing leading zeros inside each hextet and replacing one contiguous run of zero hextets with a double colon. The double colon may appear only once to keep the address unambiguous. Dotted-decimal masks and removal of trailing zeros are not valid, since they would either mix IPv4 conventions or alter the numeric value of the address.

Answer

An IPv6 address can contain multiple double colon sequences as long as each replaces a different zero run.

Answer

The IPv6 prefix length is expressed in dotted-decimal notation following a space, such as 2001:db8::1 255.255.255.0.

Answer

Trailing zeros at the end of a hextet may be removed to shorten the address, so 2001:0db0::1 can be written as 2001:0db::1.

Question 6

A technician is terminating a UTP cable and notices that the plastic clip on the RJ-45 connector is broken. What is the most likely consequence of using this connector for a network endpoint?

Accepted Answer

The connection will experience intermittent link drops.. The RJ-45 retention clip locks the connector into the port and maintains consistent contact pressure between the eight gold pins and the port's contacts. A broken clip allows the plug to slide slightly, breaking or degrading individual pin contacts, which produces intermittent link drops and CRC errors. The link may come up and then drop repeatedly as the cable shifts.

Answer

The cable will only support half-duplex speeds.

Answer

The cable will cause a short circuit in the switch.

Answer

Data will be transmitted without encryption.

Question 7

A network engineer needs to allocate a subnet for a link connecting two routers. Which prefix provides the most efficient addressing for a point-to-point connection?

Accepted Answer

/30. A /30 mask leaves 2 host bits, yielding exactly 2 usable addresses — one for each router interface on the point-to-point link. That is the minimum needed for a functional link, so /30 is the most efficient allocation without wasting addresses.

Answer

/24

Answer

/28

Answer

/29

Question 8

Which IPv6 address type is represented by the prefix fe80::/10?

Accepted Answer

Link-Local. The fe80::/10 prefix is reserved for Link-Local addresses in IPv6. These addresses are automatically configured on all IPv6-enabled interfaces and are essential for neighbor discovery and routing protocol communication on a single local link. Unlike global unicast addresses, these are not routable outside the local segment, making them fundamental for basic connectivity and troubleshooting in IPv6 environments.

Answer

Global Unicast

Answer

Unique Local

Answer

Multicast

Question 9

A network technician is selecting devices to protect a corporate network from external threats. Which TWO devices provide active threat mitigation by inspecting and blocking malicious traffic? (Choose TWO).

Accepted Answer

Firewall. Network security requires a multi-layered approach to protect against diverse threats. Firewalls and Intrusion Prevention Systems (IPS) are two fundamental components that work together to secure the perimeter and internal segments. Understanding the distinct roles these technologies play helps technicians design robust networks that can both block bad traffic and detect anomalies.

Answer

Antivirus

Answer

Honeypot

Answer

Load Balancer

Question 10

A network administrator is documenting a subnet used for a point-to-point WAN link between two Cisco routers. The link is configured with the address 10.10.10.1/30. What is the network address and the usable host range for this subnet?

Accepted Answer

Network 10.10.10.0, usable hosts 10.10.10.1 through 10.10.10.2. A /30 prefix provides two host bits, yielding exactly four addresses per subnet: one network, two usable hosts, and one broadcast. For the address 10.10.10.1/30, the subnet boundaries are multiples of four, so the network is 10.10.10.0, usable hosts are .1 and .2, and the broadcast is .3. This design is common on point-to-point links because it conserves address space.

Answer

Network 10.10.10.0, usable hosts 10.10.10.1 through 10.10.10.4

Answer

Network 10.10.10.4, usable hosts 10.10.10.5 through 10.10.10.6

Answer

Network 10.10.10.1, usable hosts 10.10.10.2 through 10.10.10.3

Question 11

Which protocol operates at the Application layer of the TCP/IP model and is used to resolve hostnames into IP addresses?

Accepted Answer

DNS. DNS (Domain Name System) operates at the Application layer of the TCP/IP model and is responsible for resolving human-readable hostnames (like www.example.com) into IP addresses. It uses UDP port 53 for standard queries and TCP port 53 for zone transfers and large responses.

Answer

DHCP

Answer

ARP

Answer

HTTP

Question 12

A network administrator needs to ensure that data remains confidential during transit across an untrusted network. Which protocol implementation best addresses this requirement?

Accepted Answer

SSH. SSH (Secure Shell) provides encrypted, authenticated communication over untrusted networks, typically on TCP port 22, using strong cryptographic algorithms to protect data in transit. It replaces insecure remote-access protocols like Telnet by encrypting the entire session, ensuring confidentiality and integrity. This directly satisfies the requirement that data remain confidential during transit.

Answer

Telnet

Answer

HTTP

Answer

SNMPv1

Question 13

Which TWO of the following statements regarding IPv6 address representation are accurate?

Accepted Answer

Leading zeros in a 16-bit field can be omitted.. Option B is correct because RFC 4291 allows leading zeros within any 16-bit hexadecimal field (hextet) to be dropped, so 0db8 can be written as db8. Option D is correct because the double-colon (::) is the compression notation that stands in for one or more consecutive 16-bit groups that are all zeros, and it may appear only once in an address. Option A is wrong because :: can be used only a single time per address; using it twice would make the number of omitted zero groups ambiguous. Option C is wrong because IPv6 addresses are commonly written in compressed form, not always as a full 32-character hexadecimal string. Option E is wrong because only leading zeros may be omitted; trailing zeros are significant and must be retained.

Answer

The double-colon (::) can be used multiple times in a single IPv6 address to shorten it.

Answer

An IPv6 address must always be written in full 32-character hexadecimal format.

Answer

Trailing zeros in a 16-bit field can be omitted.

Question 14

An administrator needs to subnet the 192.168.10.0/24 network into subnets that can support at least 25 hosts each. Which subnet mask provides the maximum number of subnets while meeting the host requirement?

Accepted Answer

255.255.255.224. To support at least 25 hosts, the subnet must have at least 5 host bits (2^5 - 2 = 30 usable hosts). A /27 mask (255.255.255.224) leaves 5 host bits, providing 30 usable addresses per subnet and yielding 8 subnets from a /24. This maximizes subnet count while still meeting the 25-host requirement.

Answer

255.255.255.248

Answer

255.255.255.240

Answer

255.255.255.192

Question 15

A technician is installing a new set of outdoor wireless access points. Which TWO factors are most likely to cause signal attenuation or interference for these endpoints?

Accepted Answer

Thick concrete walls and metal structures. Option A is correct because thick concrete walls and metal structures are dense physical obstructions that absorb, reflect, and scatter RF energy, causing significant signal attenuation, especially at higher frequencies like 5 GHz and 6 GHz. Option C is correct because 2.4 GHz cordless phones and microwave ovens operate in or near the 2.4 GHz ISM band and emit RF energy that overlaps with WLAN channels, producing co-channel and adjacent-channel interference. Option B is not a factor because Category 6a cabling is a wired Ethernet medium for the backhaul and does not radiate or attenuate wireless signals in a way that affects RF propagation. Option D is not a factor because PoE+ (802.3at) is simply a power-delivery standard over Ethernet and does not cause RF attenuation or interference. Option E is not a factor because an LC-to-LC fiber patch cord carries optical signals for wired backhaul and is immune to RF interference and does not affect wireless signal quality.

Answer

The use of Category 6a cabling for the backhaul

Answer

Configuring the access point for PoE+ (802.3at)

Answer

Using an LC-to-LC fiber patch cord

Question 16

What is the primary function of the Spanning Tree Protocol (STP) in a network with redundant links?

Accepted Answer

To prevent Layer 2 loops.. STP's primary function is to prevent Layer 2 loops by creating a loop-free logical topology. In a network with redundant links, STP elects a root bridge, determines root ports and designated ports, and blocks redundant ports to eliminate loops. This prevents broadcast storms and MAC address table instability that would otherwise occur due to frames circulating indefinitely.

Answer

To increase the total bandwidth of multiple links.

Answer

To assign IP addresses to switches.

Answer

To route traffic between different VLANs.

Question 17

Which tool is best suited for identifying a slow network segment caused by excessive broadcast traffic?

Accepted Answer

Protocol analyzer.. Broadcast storms or high volumes of traffic can severely degrade network performance. A protocol analyzer, or network sniffer, allows a technician to capture packets and examine the distribution of traffic types. By looking at the percentage of broadcast traffic compared to unicast traffic, one can identify if a specific segment is being overwhelmed by broadcast frames, which is critical for maintaining network latency and stability.

Answer

Cisco DNA Center.

Answer

SNMP Manager.

Answer

TDR cable tester.

Question 18

A network technician is troubleshooting a PC that cannot access internal network resources. Which TWO steps are recommended to verify if the PC is receiving a valid IP address?

Accepted Answer

Run ipconfig on the workstation.. Verifying the IP configuration is essential when network access fails. Using 'ipconfig' allows the technician to see if the PC has a valid address, subnet mask, and gateway. Checking the DHCP server configuration ensures that the scope is not exhausted and that the client is actually communicating with the server. These two steps confirm if the layer 3 addressing is correct before moving on to more complex layer 2 or routing issues.

Answer

Check the switch interface status.

Answer

Perform a traceroute to the local gateway.

Answer

Reset the switch configuration.

Question 19

A network engineer is troubleshooting a potential DHCP issue. Which THREE components are provided to a client during a successful DHCP 'Acknowledgment' (ACK) message? (Choose three.)

Accepted Answer

IP address for the client.. The DHCP ACK is the final step in the DORA process where the server confirms the lease of an IP address. Understanding the specific parameters delivered in this message is crucial for diagnosing configuration errors that affect host connectivity, name resolution, and the ability of devices to reach resources outside their local network segment.

Answer

The MAC address of the DHCP server.

Answer

The SSH private key for the management console.

Question 20

What is the primary purpose of a default gateway in an IP host configuration?

Accepted Answer

To act as an exit point for off-subnet traffic.. A default gateway is the router that a host sends packets to when the destination IP is not on the local subnet. It serves as the exit point for off-subnet traffic, allowing communication with external networks such as the internet or other subnets.

Answer

To resolve domain names to IP addresses.

Answer

To manage the assignment of dynamic IP addresses.

Answer

To filter incoming traffic from the internet.