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Question 241

Which OSI layer is responsible for logical addressing and routing?

1. Network
2. Transport
3. Session
4. Data Link

Correct Answer: 1

Explanation

The Network layer, Layer 3 of the OSI model, is responsible for logical addressing and routing traffic between different networks. IPv4 and IPv6 operate primarily at this layer, while routers use Layer 3 information to determine where packets should be forwarded. The Transport layer handles end-to-end communication, the Session layer manages communication sessions, and the Data Link layer handles frames and MAC addressing. Understanding Layer 3 is important when troubleshooting routing, subnetting, and inter-network connectivity.

Question 242

Which Ethernet cable category is commonly rated for 10 Gbps operation over standard twisted-pair distances?

1. Cat5e
2. Cat6
3. Cat6A
4. Cat3

Correct Answer: 3

Explanation

Cat6A twisted-pair cabling is commonly used for 10 Gbps Ethernet, including 10GBASE-T, over distances up to 100 meters under appropriate installation conditions. Cat5e supports Gigabit Ethernet and may support 10 Gbps over shorter distances depending on conditions, while Cat6 can also support 10 Gbps over reduced distances. Cat3 is an older cable category associated with much slower networking and voice applications. Cat6A is therefore a common choice when full 10 Gbps copper connectivity is required.

Question 243

What is the main purpose of a DNS CNAME record?

1. Identify a mail server
2. Map an alias to another hostname
3. Store an IPv4 address
4. Define a reverse lookup

Correct Answer: 2

Explanation

A DNS CNAME record creates an alias that points to another canonical hostname. For example, a hostname such as www.example.com can be configured as an alias for another hostname that contains the actual address record. CNAME records are useful when multiple names should reference the same destination without maintaining separate address records for each alias. An A record stores an IPv4 address, an MX record identifies mail servers, and a PTR record supports reverse DNS lookups.

Question 244

A network administrator needs to prevent unauthorized traffic from reaching a server subnet. Which control is most appropriate?

1. ACL
2. NTP
3. DHCP
4. SNMP

Correct Answer: 1

Explanation

An Access Control List, or ACL, can define rules that permit or deny network traffic based on criteria such as source address, destination address, protocol, and port. ACLs can be applied on routers, Layer 3 switches, firewalls, and other network devices depending on the platform. NTP synchronizes time, DHCP provides network configuration, and SNMP supports monitoring. When a network administrator needs to restrict traffic reaching a particular subnet, an appropriately configured ACL can provide the required traffic filtering.

Question 245

Which IPv4 address range is reserved for APIPA?

1. 169.254.0.0/16
2. 172.16.0.0/12
3. 192.168.0.0/16
4. 127.0.0.0/8

Correct Answer: 1

Explanation

Automatic Private IP Addressing, or APIPA, uses the IPv4 range 169.254.0.0/16. A host may automatically assign itself an address from this range when it is configured for DHCP but cannot successfully obtain a lease. APIPA addresses allow limited local communication but generally do not provide normal routed network connectivity. The 172.16.0.0/12 and 192.168.0.0/16 ranges are private IPv4 ranges, while 127.0.0.0/8 is reserved for loopback communication.

Question 246

Which technology allows a network device to supply electrical power over Ethernet cabling?

1. VLAN
2. PoE
3. NAT
4. QoS

Correct Answer: 2

Explanation

Power over Ethernet, or PoE, allows compatible network devices to receive electrical power through Ethernet cabling while also carrying network traffic. PoE can power devices such as wireless access points, IP cameras, VoIP phones, and some IoT equipment. This reduces the need for separate electrical outlets near each device. VLANs provide logical segmentation, NAT translates addresses, and QoS manages traffic priorities. PoE is especially useful when devices are installed in locations where providing separate power infrastructure would be difficult or expensive.

Question 247

Which routing protocol is designed primarily for exchanging routes between autonomous systems?

1. RIP
2. OSPF
3. BGP
4. EIGRP

Correct Answer: 3

Explanation

Border Gateway Protocol, or BGP, is designed to exchange routing information between autonomous systems. It is widely used for inter-domain routing and plays a central role in how routes are exchanged across large networks, including the internet. BGP uses path attributes and policies to select routes rather than relying only on a simple distance metric. OSPF and RIP are generally used as interior routing protocols within autonomous systems. BGP is therefore the protocol most associated with inter-AS routing.

Question 248

What is the primary purpose of a patch panel?

1. Encrypt network traffic
2. Organize and terminate network cables
3. Assign IP addresses
4. Route packets

Correct Answer: 2

Explanation

A patch panel provides a centralized location for terminating and organizing network cables. It allows permanent horizontal or backbone cabling to be connected to network equipment using short patch cables. This arrangement improves cable management and makes moves, additions, and changes easier to perform without repeatedly disturbing permanent cabling. Patch panels do not route packets, assign IP addresses, or encrypt traffic. They are passive physical infrastructure components commonly installed in network racks or telecommunications rooms.

Question 249

Which protocol provides secure remote command-line administration of network devices?

1. Telnet
2. FTP
3. SSH
4. TFTP

Correct Answer: 3

Explanation

Secure Shell, or SSH, provides encrypted remote command-line access to network devices and servers. It protects credentials and administrative communication from being transmitted in clear text and commonly uses TCP port 22. Telnet can provide remote command-line access but does not encrypt the session by default. FTP and TFTP are primarily file-transfer protocols rather than secure remote management protocols. SSH is therefore commonly preferred for securely administering routers, switches, firewalls, servers, and other network-enabled systems.

Question 250

A technician notices that VoIP calls contain irregular delays between packets. Which metric should be investigated?

1. Bandwidth
2. Jitter
3. MTU
4. MAC address

Correct Answer: 2

Explanation

Jitter measures variation in packet arrival timing. It can significantly affect real-time applications such as VoIP, video conferencing, and streaming because voice or video packets need to arrive at relatively consistent intervals. High jitter can produce choppy audio, distortion, or interruptions. Bandwidth describes link capacity, MTU defines the maximum packet size for a network interface, and a MAC address identifies a Layer 2 interface. When voice traffic experiences inconsistent packet timing, jitter should be examined along with latency and packet loss.

Question 251

Which IPv6 mechanism allows a host to automatically configure an address using router advertisements?

1. SLAAC
2. NAT
3. APIPA
4. PAT

Correct Answer: 1

Explanation

Stateless Address Autoconfiguration, or SLAAC, allows IPv6 hosts to automatically configure addresses using information provided by IPv6 routers. Router Advertisement messages contain network prefix information that helps hosts generate their own addresses. SLAAC can operate without requiring a traditional DHCP server for basic address configuration. APIPA is an IPv4 mechanism, while NAT and PAT are address translation technologies. SLAAC simplifies IPv6 deployment by allowing hosts to configure addressing automatically based on information received from local routers.

Question 252

Which device is designed to distribute incoming application traffic across multiple servers?

1. Modem
2. Repeater
3. Load balancer
4. Media converter

Correct Answer: 3

Explanation

A load balancer distributes incoming client requests across multiple servers or service instances. This can improve resource utilization, scalability, and availability because traffic does not need to depend on a single backend server. Depending on its design, a load balancer can make decisions using Layer 4 information such as TCP ports or Layer 7 information such as HTTP requests. A modem connects to service-provider networks, a repeater regenerates signals, and a media converter changes physical media types.

Question 253

Which protocol is commonly used to synchronize clocks across network devices?

1. DNS
2. NTP
3. LDAP
4. SMB

Correct Answer: 2

Explanation

Network Time Protocol, or NTP, synchronizes system clocks across network-connected devices. Accurate time is important for authentication, logging, troubleshooting, certificates, scheduled tasks, and security investigations. Network devices can synchronize their clocks with configured NTP servers, helping maintain consistent timestamps throughout an organization. DNS resolves names, LDAP provides directory access, and SMB supports file and resource sharing. NTP is therefore an important network service for maintaining consistent and reliable time across servers, workstations, routers, switches, and other systems.

Question 254

Which IPv6 address type is intended for communication with the nearest member of a group of interfaces?

1. Multicast
2. Unicast
3. Anycast
4. Broadcast

Correct Answer: 3

Explanation

IPv6 anycast allows the same address to be assigned to multiple interfaces, with traffic typically delivered to the nearest or best destination according to the routing topology. This can be useful for distributed services where clients should reach an appropriate nearby instance. IPv6 does not use traditional broadcast addressing. Unicast identifies one interface, while multicast delivers traffic to multiple subscribed interfaces. Anycast is therefore useful when multiple systems provide the same service and traffic should reach an appropriate instance based on routing.

Question 255

What does MTU define on a network interface?

1. Maximum frame or packet size supported
2. Minimum cable length
3. Maximum number of VLANs
4. Number of available IP addresses

Correct Answer: 1

Explanation

Maximum Transmission Unit, or MTU, defines the largest Layer 3 packet size that can normally be transmitted over an interface without fragmentation at that point. A common Ethernet MTU is 1500 bytes. If a packet exceeds the supported MTU, fragmentation or another mechanism may be required depending on the protocol and network configuration. Incorrect MTU settings can cause connectivity problems, especially across VPNs or networks with different link requirements. MTU is unrelated to VLAN count, cable length, or IP address capacity.

Question 256

Which protocol is commonly used for centralized authentication and authorization of network users?

1. RADIUS
2. TFTP
3. RTP
4. ARP

Correct Answer: 1

Explanation

RADIUS is commonly used to provide centralized authentication, authorization, and accounting services for network access. It is frequently integrated with wireless networks, VPN services, and network access control systems. A centralized authentication server allows administrators to manage user access without maintaining separate credentials on every network device. TFTP provides simple file transfers, RTP transports real-time media, and ARP resolves IPv4 addresses to MAC addresses. RADIUS is therefore well suited to centralized control of network access credentials and policies.

Question 257

Which wireless issue occurs when nearby access points use overlapping channels and interfere with each other?

1. DNS poisoning
2. Channel interference
3. DHCP starvation
4. VLAN hopping

Correct Answer: 2

Explanation

Channel interference occurs when wireless transmissions overlap in frequency and compete for the same or nearby radio resources. It can reduce throughput, increase retransmissions, and cause unstable wireless performance. Proper channel planning, suitable channel widths, and site surveys can help reduce interference. DNS poisoning affects name resolution, DHCP starvation attempts to exhaust address leases, and VLAN hopping targets network segmentation. Wireless administrators should consider both co-channel interference and adjacent-channel interference when diagnosing poor Wi-Fi performance.

Question 258

Which protocol is commonly used to collect monitoring information from network devices?

1. SNMP
2. SMTP
3. SSH
4. SFTP

Correct Answer: 1

Explanation

Simple Network Management Protocol, or SNMP, is commonly used to monitor network devices and collect operational information. Monitoring platforms can query values such as interface status, traffic counters, CPU utilization, memory usage, and other management data. SNMP can also support notifications through mechanisms such as traps. SMTP is used for email transport, SSH provides secure remote administration, and SFTP provides secure file transfers. SNMP helps administrators maintain visibility into network health and identify potential problems before they cause significant service disruption.

Question 259

Which IPv4 subnet mask corresponds to a /28 prefix?

1. 255.255.255.0
2. 255.255.255.128
3. 255.255.255.240
4. 255.255.255.252

Correct Answer: 3

Explanation

A /28 IPv4 prefix contains 28 network bits and leaves 4 host bits. The corresponding subnet mask is 255.255.255.240. This provides 16 total addresses within each subnet, with 14 traditionally usable host addresses when standard network and broadcast reservations apply. A /24 mask is 255.255.255.0, /25 is 255.255.255.128, and /30 is 255.255.255.252. Understanding CIDR notation and subnet masks is essential when designing networks and determining address ranges.

Question 260

Which technology creates a secure encrypted tunnel between a remote user and a private network?

1. VLAN
2. Remote-access VPN
3. STP
4. LACP

Correct Answer: 2

Explanation

A remote-access VPN creates a secure tunnel between an individual user’s device and a private network across an untrusted network such as the internet. Depending on the technology, the VPN can provide encryption, authentication, and integrity protection for traffic traveling through the tunnel. VLANs provide Layer 2 segmentation, STP prevents switching loops, and LACP combines physical links into a logical connection. Remote-access VPNs are commonly used when employees or administrators need secure access to internal resources from outside the organization.