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Question 121

What protocol translates private IP addresses to public addresses?

1. Address Resolution Protocol
2. Dynamic Host Configuration Protocol
3. Network Address Translation
4. Domain Name System

Correct Answer: 3

Explanation:

Network Address Translation is a technique used primarily to conserve IPv4 address space by mapping an entire local network of private, non-routable IP addresses onto a single public, routable IP address provided by an Internet Service Provider. As internal packets traverse the NAT router heading outward to the public internet, source IP headers are modified to display the public address. When return traffic arrives, the router translates the public destination back to the appropriate internal private IP address, maintaining session state integrity and enhancing internal network security by hiding internal network topologies from external observers.

Question 122

Which OSI layer provides reliable end-to-end data delivery?

1. Physical Layer
2. Transport Layer
3. Network Layer
4. Application Layer

Correct Answer: 2

Explanation:

The Transport layer, which is Layer 4 of the OSI reference model, is fundamentally responsible for providing reliable, transparent, and error-checked end-to-end data delivery between communicating hosts. Protocols operating at this layer, such as Transmission Control Protocol, establish connection-oriented sessions, implement flow control mechanisms, utilize windowing to optimize bandwidth utilization, and perform error detection and retransmission of lost segments. This ensures that application data streams are delivered accurately, in correct sequence, and without corruption regardless of the underlying physical network infrastructure traversed.

Question 123

What is the default subnet mask for Class A?

1. 255.0.0.0
2. 255.255.0.0
3. 255.255.255.0
4. 255.255.255.255

Correct Answer: 1

Explanation:

In traditional classful IPv4 addressing, Class A networks are designated for extremely large-scale enterprise or governmental networks and utilize a default subnet mask of 255.0.0.0. In binary representation, this corresponds to eight network bits followed by twenty-four host bits. This mask indicates that the first octet of the IP address identifies the specific network segment, while the final three octets are available for host device identification. This configuration allows a maximum of 16,777,214 usable host IP addresses per network segment after reserving the network identifier and broadcast addresses.

Question 124

Which network device operates primarily at Layer 2?

1. Enterprise Core Router
2. Traditional Network Hub
3. Application Layer Firewall
4. Layer 2 Ethernet Switch

Correct Answer: 4

Explanation:

A Layer 2 Ethernet switch operates at the Data Link layer of the OSI model and makes forwarding decisions based exclusively on hardware Media Access Control addresses embedded within Ethernet frames. When a frame enters a switch port, the device examines the source MAC address and records it in its Content Addressable Memory table to map port locations. It then looks up the destination MAC address to forward the frame only to the specific port connected to the target device, thereby reducing unnecessary network traffic and minimizing collision domains across the local network infrastructure.

Question 125

What protocol dynamically resolves IP addresses to MAC addresses?

1. Domain Name System
2. Address Resolution Protocol
3. Dynamic Host Configuration Protocol
4. Simple Network Management Protocol

Correct Answer: 2

Explanation:

The Address Resolution Protocol is an essential networking protocol operating within the Internet Protocol suite used to map logical Layer 3 IPv4 addresses to physical Layer 2 MAC addresses. When a host needs to communicate with another device on the same local network segment, it knows the destination IP address but requires the corresponding hardware MAC address to construct a valid Ethernet frame. The sending host broadcasts an ARP request packet asking the owner of the target IP address to reply with its MAC address, enabling successful frame encapsulation and transmission.

Question 126

Which cable type resists electromagnetic interference completely today?

1. Unshielded Twisted Pair
2. Shielded Twisted Pair
3. Fiber Optic Cable
4. Coaxial Copper Cable

Correct Answer: 3

Explanation:

A fiber optic cable consists of one or more extremely thin strands of glass or plastic fiber encased in protective cladding and outer jackets. Data is transmitted across fiber optic cables as pulses of light generated by lasers or light-emitting diodes. Because optical transmission relies on light rather than electrical current, fiber optic cables are entirely immune to electromagnetic interference and radio frequency interference generated by power lines, motors, or fluorescent lighting. They support significantly higher bandwidth capacities and much longer transmission distance limitations compared to traditional copper-based cabling media.

Question 127

What is the decimal value of binary 10000000?

1. 128
2. 192
3. 224
4. 240

Correct Answer: 1

Explanation:

To convert the binary octet 10000000 to decimal, calculate the sum of the powers of two corresponding to each bit position containing a binary one, moving from right to left starting at two to the power of zero. The left-most bit represents 128. Since all other seven bits are zeros, the total decimal value is simply 128. This value represents the exact boundary value utilized in various IPv4 subnet masks, such as /25 prefixes, and serves as a fundamental building block in binary arithmetic calculations for network engineering and IP subnet design.

Question 128

Which IEEE standard defines standard wired Ethernet networks?

1. IEEE 802.11
2. IEEE 802.1Q
3. IEEE 802.1X
4. IEEE 802.3

Correct Answer: 4

Explanation:

The IEEE 802.3 standard family defines the physical layer and data link layer media access control specifications for wired Ethernet local area networks. Over decades of evolution, 802.3 has expanded from early coaxial implementations to encompass twisted pair copper cabling standards such as 10BASE-T, 100BASE-TX, and 1000BASE-T, as well as various optical fiber standards. In contrast, IEEE 802.11 governs wireless local area networks, IEEE 802.1Q specifies Virtual Local Area Network tagging on Ethernet frames, and IEEE 802.1X provides port-based network access control authentication mechanisms.

Question 129

What protocol dynamically assigns IP configuration parameters to hosts?

1. Domain Name System
2. Dynamic Host Configuration Protocol
3. Address Resolution Protocol
4. Network Time Protocol

Correct Answer: 2

Explanation:

The Dynamic Host Configuration Protocol is a network management protocol used to automate the configuration of devices connected to an IP network. Instead of manually assigning static IP addresses, subnet masks, default gateways, and DNS server addresses to every individual workstation, a DHCP server leases these configuration parameters dynamically from a predefined address pool. This eliminates manual configuration errors, optimizes IP address utilization through temporary lease expirations, and simplifies network administration across enterprise environments, allowing seamless client onboarding and mobility.

Question 130

Which switching method verifies frame check sequences before forwarding?

1. Cut-through switching
2. Fragment-free switching
3. Store-and-forward switching
4. Direct-access switching

Correct Answer: 3

Explanation:

In store-and-forward switching, the switch receives the entire Ethernet frame into its internal memory buffer before taking any forwarding action. Once the complete frame is received, the switch performs a Cyclic Redundancy Check by analyzing the Frame Check Sequence trailer to verify frame integrity, checking for mathematical errors, corrupted bits, and runt frames. Only if the frame passes validation does the switch examine the destination MAC address, look up the forwarding table, and forward the frame out the appropriate egress port, ensuring error-free transmission across the network.

Question 131

What is the broadcast address for subnet 192.168.2.0?

1. 192.168.2.255
2. 192.168.2.0
3. 192.168.2.1
4. 192.168.2.254

Correct Answer: 1

Explanation:

In any standard IPv4 subnet utilizing a default /24 prefix, the network identifier is represented by setting all host bits to zero, while the broadcast address is represented by setting all host bits to binary ones. For the network 192.168.2.0 with a subnet mask of 255.255.255.0, the first three octets represent the network portion and remain fixed. The final octet represents the host portion, which contains eight bits. Setting all eight host bits to binary ones results in decimal 255, establishing 192.168.2.255 as the broadcast address utilized to reach all devices on that specific subnet.

Question 132

Which transport layer protocol utilizes connectionless datagram delivery?

1. Transmission Control Protocol
2. Secure Shell Protocol
3. File Transfer Protocol
4. User Datagram Protocol

Correct Answer: 4

Explanation:

The User Datagram Protocol is a core transport layer protocol that provides a simple, connectionless communication service without flow control, error recovery, or packet retransmission guarantees. Unlike Transmission Control Protocol, which establishes a formal handshake and tracks sequence numbers for reliable delivery, UDP transmits datagrams immediately without verifying receiver availability or acknowledgment. This makes UDP ideal for real-time applications such as Voice over IP, video streaming, and online gaming, where low latency is critical and occasional lost packets are preferable to transmission delays.

Question 133

What is the primary purpose of IPv4 subnetting?

1. Encrypting payload data across insecure wireless links.
2. Dividing a single network into smaller sub-networks.
3. Translating private internal addresses to public IPs.
4. Automatically assigning hostnames to local workstations.

Correct Answer: 2

Explanation:

Subnetting is the strategic practice of dividing a single large physical IP network into multiple smaller, logically distinct sub-networks. By borrowing bits from the host portion of an IPv4 address and reallocating them to the network mask, network administrators reduce broadcast domain size, improve overall network performance, enhance security isolation between departments, and conserve scarce IPv4 address space. Subnetting enables efficient routing table summarization and structured organizational planning across complex enterprise network topologies.

Question 134

Which TCP flag is used to initiate connections?

1. ACK
2. FIN
3. SYN
4. RST

Correct Answer: 3

Explanation:

The Synchronize flag is utilized during the initial phase of the Transmission Control Protocol three-way handshake to establish a reliable connection between two network hosts. The connection sequence begins when the client sends a segment containing the SYN flag and an initial sequence number to the server. The server responds with a SYN-ACK segment acknowledging the request and providing its own sequence number. Finally, the client replies with an ACK packet, confirming receipt and completing the handshake so data transmission can commence securely.

Question 135

What is the primary purpose of spanning tree protocol?

1. Preventing network loops in redundant switched topologies.
2. Encrypting data frames traversing through trunk ports.
3. Automatically assigning dynamic IP addresses to clients.
4. Translating domain names into numerical IP addresses.

Correct Answer: 1

Explanation:

Spanning Tree Protocol is a Layer 2 loop-prevention mechanism designed to ensure a loop-free logical topology across redundant physical switch links. In enterprise networks, redundant links are frequently deployed to guarantee high availability; however, unmanaged loops can cause broadcast storms, multiple frame copies, and catastrophic MAC table instability. STP calculates an optimal loop-free path across the bridged network, automatically placing redundant ports into a blocking state so they can instantly transition to a forwarding state if a primary link failure occurs.

Question 136

Which traditional device operates at Layer 1 exclusively?

1. Layer 2 Switch
2. Multilayer Switch
3. Enterprise Router
4. Network Hub

Correct Answer: 4

Explanation:

A traditional network hub operates strictly at Layer 1, the physical layer of the OSI reference model. When a hub receives an electrical or optical signal on one of its ports, it simply regenerates that signal and broadcasts it out all other active ports without examining header information, MAC addresses, or packet contents. Because hubs do not filter traffic or establish separate collision domains, all connected devices share a single collision domain and a single broadcast domain, leading to increased contention and potential performance degradation in busy network environments.

Question 137

What CIDR notation corresponds to subnet mask 255.255.255.128?

1. /24
2. /25
3. /26
4. /27

Correct Answer: 2

Explanation:

CIDR notation represents the number of continuous network bits set to binary one within an IPv4 subnet mask. To determine the CIDR prefix for 255.255.255.128, evaluate the final octet 128 in binary form, which is 10000000. This octet contains one bit set to one and seven bits set to zero. The first three octets equal twenty-four network bits. Adding the single bit from the final octet gives a total of twenty-five network bits, resulting in a /25 prefix notation, which provides one hundred twenty-eight total IP addresses per subnet.

Question 138

Which protocol provides secure remote command-line network management?

1. Telnet
2. HTTP
3. Secure Shell
4. Simple Network Management Protocol

Correct Answer: 3

Explanation:

Secure Shell is a cryptographic network protocol designed for operating network services securely over an unsecured network. In enterprise networking environments, SSH is used as a secure replacement for legacy Telnet sessions when administrators remotely log into routers, switches, and firewalls to execute command line configurations. Unlike Telnet, which transmits all authentication credentials, usernames, passwords, and command keystrokes in plain text across the network where they can be easily intercepted, SSH encrypts all transmitted data streams to prevent unauthorized eavesdropping.

Question 139

What header field prevents packets from looping infinitely?

1. Time to Live
2. Total Length
3. Protocol Identifier
4. Header Checksum

Correct Answer: 1

Explanation:

The Time to Live field in the IPv4 header is an 8-bit integer designed to prevent packets from circulating indefinitely inside a misconfigured routing loop. Every router that processes and forwards the packet decrements the TTL value by one. If the TTL counter reaches zero before the packet arrives at its final destination, the router drops the packet and generates an Internet Control Message Protocol Time Exceeded error message back to the original source host. This mechanism protects network bandwidth from exhaustion caused by routing loops.

Question 140

Which routing source has an administrative distance of zero?

1. Static Route
2. OSPF Route
3. EIGRP Route
4. Directly Connected Route

Correct Answer: 4

Explanation:

Administrative distance represents the trustworthiness or preference level of a routing information source, where lower values indicate higher reliability. In Cisco IOS routing architecture, directly connected interface routes are assigned an administrative distance of zero, representing absolute trustworthiness because the router resides physically on that network segment. Static routes carry an administrative distance of one, while dynamic routing protocols like OSPF and EIGRP possess higher default values such as 110 and 90, establishing a clear hierarchy for path selection.