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Question: 381. Which protocol is used by IPv6 devices to detect duplicate addresses before using them?

1. DHCP
   2. ARP
   3. Duplicate Address Detection
   4. SMTP

Correct Answer: 3. Duplicate Address Detection

Explanation:

Duplicate Address Detection, or DAD, is an IPv6 Neighbor Discovery function used to determine whether an IPv6 address is already in use on the local network. Before assigning an address to an interface, an IPv6 host can send a Neighbor Solicitation message to check for another device using the same address. This helps prevent address conflicts. IPv6 does not use ARP for this function. DHCP may provide configuration, while SMTP is associated with email transmission.

Question: 382. Which device separates broadcast domains by default?

1. Hub
   2. Router
   3. Repeater
   4. Layer 1 media converter

Correct Answer: 2. Router

Explanation:

A router separates broadcast domains because broadcast traffic received on one routed interface is not normally forwarded to another routed interface. Each routed interface represents a different Layer 3 network. Hubs and repeaters operate at lower layers and do not create separate broadcast domains. Layer 2 switches also normally form a single broadcast domain per VLAN unless VLAN segmentation is configured. Therefore, a router is the device traditionally used to separate broadcast domains.

Question: 383. Which command can display the IP configuration of a Windows host?

1. ipconfig
   2. chmod
   3. routeprint
   4. hostnamectl

Correct Answer: 1. ipconfig

Explanation:

The Windows ipconfig command displays IP configuration information for network interfaces. Depending on the options used, it can show IPv4 and IPv6 addresses, subnet masks, default gateways, DNS-related information, and DHCP details. It is commonly used during network troubleshooting to verify whether a host has received the expected configuration. Other commands may perform different administrative functions, but ipconfig is the standard Windows command for viewing basic IP configuration information.

Question: 384. Which IPv4 address class traditionally contains addresses beginning with values from 1 through 126 in the first octet?

1. Class D
   2. Class C
   3. Class A
   4. Class B

Correct Answer: 3. Class A

Explanation:

In the historical classful IPv4 addressing system, Class A addresses used first-octet values from 1 through 126. Class B traditionally covered 128 through 191, Class C covered 192 through 223, and Class D was reserved for multicast. Although modern IPv4 networks use CIDR rather than relying on these historical classes for routing, the classful categories remain relevant when studying networking fundamentals. Therefore, the traditional Class A range begins with first-octet values from 1 through 126.

Question: 385. What is the main purpose of a DNS A record?

1. Map a hostname to an IPv4 address
   2. Map an IPv6 address to a hostname
   3. Identify a mail server
   4. Specify a VLAN ID

Correct Answer: 1. Map a hostname to an IPv4 address

Explanation:

A DNS A record associates a hostname with an IPv4 address. When a client queries DNS for a hostname that has an A record, the DNS response can provide the corresponding IPv4 address so the client can establish communication. An AAAA record is used for IPv6 addresses, while MX records identify mail-exchange servers. VLAN IDs are unrelated to DNS records. Therefore, the A record is specifically used to map a hostname to an IPv4 address.

Question: 386. Which protocol provides centralized authentication, authorization, and accounting services for network access?

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

Correct Answer: 1. RADIUS

Explanation:

RADIUS, or Remote Authentication Dial-In User Service, provides centralized authentication, authorization, and accounting capabilities. It is commonly used for network access services such as wireless authentication, VPN access, and administrative login environments. A centralized authentication server can validate user credentials and return authorization information to the requesting network device. ARP handles IPv4 address resolution, ICMP provides network control messages, and TFTP provides simple file transfer. Therefore, RADIUS is the protocol associated with centralized AAA services in many network environments.

Question: 387. Which IPv6 prefix identifies link-local addresses?

1. 2000::/3
   2. FE80::/10
   3. FF00::/8
   4. FC00::/7

Correct Answer: 2. FE80::/10

Explanation:

IPv6 link-local addresses use the FE80::/10 prefix. These addresses are intended for communication on the local network link and are not routed beyond that link. They are important for Neighbor Discovery and other local IPv6 operations. The 2000::/3 range is associated with global unicast addressing, FF00::/8 is the multicast range, and FC00::/7 is associated with unique local addresses. Therefore, FE80::/10 is the correct prefix for IPv6 link-local addresses.

Question: 388. Which feature allows a network administrator to prioritize certain types of traffic over less time-sensitive traffic?

1. QoS
   2. NAT
   3. ARP
   4. DHCP

Correct Answer: 1. QoS

Explanation:

Quality of Service, or QoS, provides mechanisms for classifying, prioritizing, queuing, and managing network traffic. It can be especially useful for applications such as voice and video that are sensitive to delay, jitter, and packet loss. QoS policies can prioritize important traffic when network resources are congested. NAT translates addresses, ARP performs IPv4-to-MAC resolution, and DHCP provides host configuration. Therefore, QoS is the technology used to manage traffic priority and improve predictable application performance.

Question: 389. Which IPv4 prefix represents a network containing 16 addresses?

1. /24
   2. /30
   3. /28
   4. /27

Correct Answer: 3. /28

Explanation:

An IPv4 /28 network contains 16 total addresses because there are 4 host bits remaining, and 2^4 = 16. In a traditional subnet, some addresses are reserved for the network and broadcast addresses, leaving 14 normally usable host addresses. A /30 contains 4 total addresses, a /27 contains 32, and a /24 contains 256. Understanding the relationship between prefix length and address count is essential for IPv4 subnetting and address planning.

Question: 390. Which protocol is commonly used to automatically discover neighboring network devices on HPE networking equipment and other standards-compliant devices?

1. LLDP
   2. SMTP
   3. FTP
   4. POP3

Correct Answer: 1. LLDP

Explanation:

LLDP, or Link Layer Discovery Protocol, allows network devices to advertise and learn information about directly connected neighbors. It can provide details such as device identity, port information, system capabilities, and management information. This is useful for documenting topology and troubleshooting physical connections. Because LLDP is a standards-based protocol, it can operate between devices from different vendors when both support it. SMTP, FTP, and POP3 are application-layer protocols unrelated to Layer 2 neighbor discovery.

Question: 391. What happens when a router receives a packet whose destination matches no specific routing-table entry and no default route exists?

1. It forwards the packet to every interface
   2. It normally discards the packet
   3. It converts the packet to a broadcast
   4. It sends it to the DNS server

Correct Answer: 2. It normally discards the packet

Explanation:

If a router cannot find a matching route for a packet’s destination and there is no default route available, it normally has no valid forwarding path. The router therefore discards the packet. Depending on the circumstances and configuration, it may send an ICMP Destination Unreachable message back toward the source. A router does not normally broadcast an unroutable packet through all interfaces or forward it to a DNS server. Understanding this behavior is useful when diagnosing missing routes and connectivity failures.

Question: 392. Which protocol is commonly used to provide secure web communication?

1. HTTP
   2. HTTPS
   3. TFTP
   4. Telnet

Correct Answer: 2. HTTPS

Explanation:

HTTPS is HTTP carried over a secure TLS connection. It provides encryption and helps protect the confidentiality and integrity of information exchanged between a client and web server. It can also provide authentication of the server through digital certificates. Plain HTTP does not provide the same transport encryption. TFTP is a simple file-transfer protocol, while Telnet provides remote terminal access without modern encrypted-session protections. Therefore, HTTPS is the standard protocol used for secure web communication.

Question: 393. Which network metric represents the variation in packet delay over time?

1. Bandwidth
   2. Throughput
   3. Jitter
   4. MTU

Correct Answer: 3. Jitter

Explanation:

Jitter describes variation in packet delay over time. It is particularly important for real-time applications such as voice and video because inconsistent packet arrival times can negatively affect playback and conversation quality. Bandwidth represents the capacity of a link, throughput represents the actual rate of successful data transfer, and MTU represents the maximum transmission unit size. Therefore, jitter is the network performance metric associated with variation in packet delay.

Question: 394. Which Ethernet frame size is the standard maximum payload size for a normal Ethernet frame without considering additional jumbo-frame configurations?

1. 64 bytes
   2. 1518 bytes
   3. 9000 bytes
   4. 1500 bytes

Correct Answer: 4. 1500 bytes

Explanation:

The standard Ethernet Maximum Transmission Unit, or MTU, for an IP payload is commonly 1500 bytes. The complete standard Ethernet frame can be up to 1518 bytes when the Ethernet header and Frame Check Sequence are included, excluding certain additional tagging considerations. Jumbo frames can support larger payloads, such as around 9000 bytes, when supported throughout the network path. The 64-byte value represents the minimum Ethernet frame size rather than the standard maximum IP payload.

Question: 395. Which protocol can be used to transfer a device configuration or firmware file using a simple, connectionless file-transfer mechanism?

1. TFTP
   2. HTTPS
   3. SSH
   4. IMAP

Correct Answer: 1. TFTP

Explanation:

TFTP, or Trivial File Transfer Protocol, provides a simple file-transfer mechanism using UDP. It has fewer features and less overhead than protocols such as FTP and SFTP and does not provide built-in encryption. TFTP has historically been used for tasks such as transferring network-device configurations or boot images in controlled environments. HTTPS provides secure web communication, SSH provides secure remote access, and IMAP is used for email retrieval. Therefore, TFTP is the protocol associated with simple connectionless file transfers.

Question: 396. Which network design concept places devices into separate security zones based on their role or trust level?

1. Segmentation
   2. Broadcast amplification
   3. Port mirroring
   4. Address resolution

Correct Answer: 1. Segmentation

Explanation:

Network segmentation divides infrastructure into separate logical or physical zones based on factors such as function, trust level, user group, or security requirements. For example, guest systems, employee workstations, servers, and management devices can be placed into different segments and controlled with routing or firewall policies. Segmentation can reduce unnecessary communication and limit the scope of security incidents. Port mirroring is used for traffic analysis, while address resolution maps network-layer addresses to link-layer addresses. Therefore, segmentation is the appropriate concept.

Question: 397. Which protocol is responsible for sending email from a mail client or server to another mail server?

1. SMTP
   2. IMAP
   3. POP3
   4. DNS

Correct Answer: 1. SMTP

Explanation:

SMTP, or Simple Mail Transfer Protocol, is used for sending email messages and transferring them between mail servers. Email clients commonly use SMTP when submitting outgoing messages to a mail service. IMAP and POP3 are primarily associated with retrieving email from mail servers, while DNS provides name-resolution services and can help locate mail servers through MX records. Therefore, SMTP is the protocol responsible for email transmission rather than mailbox retrieval.

Question: 398. Which IPv4 subnet mask provides 62 usable host addresses in a traditional subnet?

1. 255.255.255.248
   2. 255.255.255.192
   3. 255.255.255.224
   4. 255.255.255.240

Correct Answer: 2. 255.255.255.192

Explanation:

The subnet mask 255.255.255.192 corresponds to a /26 prefix. A /26 leaves 6 host bits, producing 2^6 = 64 total addresses. In the traditional IPv4 subnet model, one address is used for the network identifier and one for the broadcast address, leaving 62 usable host addresses. A /27 provides 30 usable hosts, /28 provides 14, and /29 provides 6. Therefore, /26, or 255.255.255.192, provides 62 usable addresses.

Question: 399. Which protocol is used to establish secure remote access to a network device through an encrypted terminal session?

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

Correct Answer: 2. SSH

Explanation:

SSH, or Secure Shell, provides encrypted remote terminal access to network devices and servers. It protects authentication credentials and session data during remote administration. Telnet provides similar terminal functionality but lacks the encryption expected for secure management. TFTP provides simple file transfers, while DHCP provides automatic network configuration. For secure remote command-line management, SSH is therefore the appropriate protocol. Network administrators commonly use SSH to configure and troubleshoot routers, switches, servers, and other infrastructure.

Question: 400. Which troubleshooting method involves changing only one variable at a time and checking the result?

1. Random configuration
   2. Layered troubleshooting
   3. Controlled change testing
   4. Broadcast flooding

Correct Answer: 3. Controlled change testing

Explanation:

Controlled change testing involves modifying one relevant variable at a time and then observing the result. This approach makes it easier to determine which change affected the problem and reduces the risk of introducing multiple unknown factors simultaneously. It is especially useful when troubleshooting configuration issues involving interfaces, VLANs, routing, security policies, or services. Layered troubleshooting is also valuable, but it describes progressing through network layers or functional areas rather than specifically changing one variable at a time. Controlled testing provides clearer cause-and-effect evidence.