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Question 341

Which protocol is utilized to dynamically resolve Layer 3 IPv4 addresses into Layer 2 physical hardware MAC addresses?

1. Domain Name System
2. Address Resolution Protocol
3. Dynamic Host Configuration Protocol
4. Internet Control Message Protocol

Correct Answer: 2

Explanation:

The Address Resolution Protocol operates within the Internet Protocol suite to bridge the gap between Layer 3 logical addressing and Layer 2 physical hardware addressing. When a host needs to transmit data packets to another device residing on the exact same local network segment, it knows the target device’s IPv4 address from routing lookups or application configurations. However, network interface cards cannot encapsulate packets into Ethernet frames without knowing the destination’s 48-bit physical MAC address. To resolve this, the sending host broadcasts an ARP request packet across the local network asking which device owns the specific target IPv4 address. The matching destination host responds directly with an ARP reply containing its physical hardware address, allowing subsequent Ethernet frame encapsulations to occur smoothly.

Question 342

Which IEEE standard specifies the Rapid Spanning Tree Protocol (RSTP) for high-speed network convergence?

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

Correct Answer: 3

Explanation:

The IEEE 802.1w standard defines the Rapid Spanning Tree Protocol, which was developed as a high-speed evolutionary replacement for the original IEEE 802.1D Spanning Tree Protocol. Traditional STP convergence times often ranged from thirty to fifty seconds as ports transitioned sluggishly through blocking, listening, and learning states, causing noticeable network downtime during topology changes. RSTP dramatically improves upon this architecture by introducing new port roles and state simplifications, allowing link failures and topology reconvergencies to occur in milliseconds rather than minutes. By utilizing explicit handshake mechanisms between neighboring switches on point-to-point links, RSTP eliminates legacy forwarding delays and maintains high availability across modern switched enterprise networks.

Question 343

What is the default administrative distance assigned to Open Shortest Path First (OSPF) routing protocol entries in Cisco IOS?

1. 90
2. 100
3. 110
4. 120

Correct Answer: 3

Explanation:

Administrative distance represents the trustworthiness and preference level assigned to different routing information sources on Cisco routers, where lower numerical values indicate higher reliability and priority during path selection. In Cisco IOS routing architecture, OSPF is assigned a default administrative distance of 110. This places OSPF as more trustworthy than Routing Information Protocol at 120, but less preferred than EIGRP at 90, static routes at 1, and directly connected routes at 0. When a router learns about the exact same destination network from multiple routing protocols simultaneously, its path selection algorithm evaluates the administrative distances first, preferring sources with lower values to determine the optimal active forwarding path.

Question 344

Which Cisco IOS command displays active Network Address Translation (NAT) translation table entries and operational statistics?

1. show ip route
2. show ip nat translations
3. show ip interface brief
4. show interfaces trunk

Correct Answer: 2

Explanation:

The show ip nat translations command is an essential diagnostic utility executed in privileged EXEC mode on Cisco routers configured with Network Address Translation. When invoked, it displays the active mappings between internal private IP addresses and external public IP addresses or port numbers. The output details translation types (such as static, dynamic, or overload), source and destination IP addresses, and allocated port numbers. Network administrators rely heavily on this command during troubleshooting to verify whether NAT and Port Address Translation rules are functioning correctly, confirm that internal client sessions are translating properly, and diagnose connectivity failures across wide area network boundaries.

Question 345

What is the standard IPv6 loopback address utilized by a host to test its own internal network protocol stack?

1. ::1
2. 2001:db8::1
3. fe80::1
4. ff02::1

Correct Answer: 1

Explanation:

In IPv6 architecture, the address ::1 serves as the standard loopback address, functionally equivalent to the IPv4 loopback address of 127.0.0.1. When a network application or operating system transmits a packet to ::1, the local network protocol stack loops the packet back internally without sending any data frames out across physical network interface cards or physical media. This mechanism is essential for software developers and system administrators to verify that the local IPv6 protocol stack is installed, initialized, and functioning correctly on the host machine independent of external network connectivity or physical interface status.

Question 346

Which wireless security protocol introduced robust Advanced Encryption Standard (AES) encryption combined with CCMP to replace vulnerable TKIP implementations?

1. WEP
2. WPA
3. WPA2
4. WPS

Correct Answer: 3

Explanation:

Wi-Fi Protected Access 2 was introduced by the Wi-Fi Alliance to provide robust enterprise-grade security for wireless local area networks, addressing the critical cryptographic vulnerabilities found in original WEP and transitional WPA-TKIP protocols. WPA2 mandates the use of the Advanced Encryption Standard (AES) algorithm combined with Counter Mode with Cipher Block Chaining Message Authentication Code Protocol (CCMP) to ensure strict data confidentiality, integrity, and authentication over the air. By utilizing strong cryptographic keys and secure cipher wrappers, WPA2 effectively protects enterprise wireless communications against unauthorized eavesdropping, packet injection, and cryptographic cracking attacks.

Question 347

Which TCP port is utilized by default for secure Hypertext Transfer Protocol Secure (HTTPS) web traffic?

1. Port 21
2. Port 80
3. Port 443
4. Port 8080

Correct Answer: 3

Explanation:

Hypertext Transfer Protocol Secure operates by default over Transmission Control Protocol port 443. HTTPS is the secure extension of standard HTTP, designed to protect web communications between client browsers and web servers against eavesdropping, tampering, and man-in-the-middle attacks. It achieves this security by wrapping standard HTTP data payloads inside Transport Layer Security (TLS) or Secure Sockets Layer (SSL) cryptographic encryption wrappers. Network administrators and security engineers frequently reference port 443 when configuring enterprise firewalls, proxy servers, load balancers, and Access Control Lists to permit authorized secure web traffic while blocking unauthorized application ports.

Question 348

Which Cisco IOS command displays comprehensive hardware architecture details, software image filenames, and memory utilization statistics?

1. show running-config
2. show version
3. show flash
4. show ip interface brief

Correct Answer: 2

Explanation:

The show version command executed within privileged EXEC mode on Cisco routers and switches is an invaluable diagnostic utility providing comprehensive system telemetry regarding hardware architecture, software versions, and persistent memory utilization. In addition to displaying exact Cisco IOS software image filenames, system uptime statistics, and hardware model numbers, the output explicitly details total capacity, allocated usage, and remaining free space for flash memory and non-volatile random-access memory. Administrators rely on this command during routine maintenance audits and pre-upgrade assessments to verify storage space availability before transferring new firmware images.

Question 349

What is the default OSPF hello packet interval timer on point-to-point and multi-access broadcast network links?

1. 5 seconds
2. 10 seconds
3. 30 seconds
4. 60 seconds

Correct Answer: 2

Explanation:

The Open Shortest Path First routing protocol utilizes Hello packets to discover neighboring routers, establish bidirectional communication, and maintain dynamic adjacencies within an OSPF area. On multi-access broadcast networks and point-to-point serial links, the default OSPF hello interval timer is set to 10 seconds, with a corresponding dead interval timer of 40 seconds. If a router fails to receive an incoming OSPF Hello packet from an established neighbor before the 40-second dead timer expires, it declares that neighbor dead, tears down the adjacency, and triggers a recalculation of the network topology to reroute traffic around the failed link.

Question 350

Which protocol is utilized to transmit system log messages from network devices to a centralized monitoring server?

1. Simple Network Management Protocol
2. Syslog
3. NetFlow
4. Telnet

Correct Answer: 2

Explanation:

Syslog is a standard network protocol designed to transmit system log or event messages across IP networks from routers, switches, firewalls, and servers to a centralized log collection repository. Syslog utilizes User Datagram Protocol port 514 by default to send asynchronous text notifications categorized by severity levels ranging from 0 (Emergency) to 7 (Debugging). Centralized Syslog servers are vital for enterprise network operations, enabling administrators to monitor system health, audit security events, correlate error messages across multiple devices, and conduct rapid forensic analysis during troubleshooting and incident response procedures.

Question 351

What is the block size of an IPv4 subnet configured with the subnet mask 255.255.255.192?

1. 32 addresses
2. 64 addresses
3. 128 addresses
4. 256 addresses

Correct Answer: 2

Explanation:

To determine the block size or total address count of an IPv4 subnet, network engineers subtract the decimal value of the final octet of the subnet mask from the absolute base of 256. For a subnet mask of 255.255.255.192, the decimal value in the final octet is 192. Subtracting 192 from 256 yields a precise block size of 64 total addresses per subnet. This configuration corresponds to a /26 CIDR prefix in binary notation. Out of the 64 total addresses in this block, two addresses are permanently reserved—the network identifier at the lowest boundary and the direct broadcast address at the highest boundary—leaving 62 usable host IP addresses.

Question 352

Which Cisco IOS command verifies the operational status, native VLAN assignments, and encapsulation types of active trunk ports?

1. show ip interface brief
2. show interfaces trunk
3. show cdp neighbors detail
4. show ip route

Correct Answer: 2

Explanation:

The show interfaces trunk command is an essential diagnostic and verification utility executed in privileged EXEC mode within the Cisco IOS command-line interface. When invoked, it displays all physical and logical switch ports currently operating as 802.1Q trunk links. The output details critical configuration parameters including encapsulation types in use, native VLAN assignments, operational trunk status, allowed VLANs on the trunk, and VLANs currently active in the spanning tree forwarding state. Network administrators rely heavily on this command during campus network troubleshooting to verify whether inter-switch trunking is functioning correctly.

Question 353

What is the primary operational purpose of DHCP snooping on a Cisco Catalyst switch?

1. Encrypting DHCP lease negotiation traffic across wireless links.
2. Preventing rogue DHCP servers from distributing unauthorized IP configuration parameters to client hosts.
3. Automatically balancing DHCP address lease pools across multiple distribution routers.
4. Translating private internal IP addresses into public routable addresses using port overload.

Correct Answer: 2

Explanation:

DHCP snooping is a Layer 2 security feature built into Cisco Catalyst switches that acts as a firewall between untrusted host connection ports and trusted DHCP servers. In a compromised network environment, an attacker could plug an unauthorized rogue DHCP server into a user access port and flood the local segment with malicious IP configuration parameters to launch man-in-the-middle attacks. DHCP snooping inspects incoming DHCP traffic on a per-port basis, dividing switch ports into trusted ports (connected to legitimate enterprise DHCP servers or upstream trunks) and untrusted ports (connected to end-user workstations), dropping unauthorized server replies immediately.

Question 354

Which IPv6 address type is restricted strictly to a single local link and never forwarded across routers?

1. Global Unicast Address
2. Unique Local Address
3. Link-Local Address
4. Anycast Address

Correct Answer: 3

Explanation:

An IPv6 Link-Local Address is a specialized unicast address type automatically configured on every IPv6-enabled network interface as soon as the protocol stack initializes, utilizing the reserved prefix fe80::/10. Link-local addresses are strictly restricted to the local physical or logical link where the host resides. A fundamental rule of IPv6 architecture dictates that routers must never forward packets containing link-local source or destination addresses outside the local network segment. Despite this non-routable restriction, link-local addresses are vital for core network operations, serving as mandatory source addresses for Neighbor Discovery Protocol messages and routing protocol peering sessions.

Question 355

What is the default administrative distance assigned to internal routes learned via EIGRP in Cisco IOS?

1. 90
2. 100
3. 110
4. 170

Correct Answer: 1

Explanation:

Administrative distance represents the trustworthiness and preference level assigned to different routing information sources on Cisco routers, where lower numerical values indicate higher reliability during route selection. In Cisco IOS routing architecture, internal routes learned via the Enhanced Interior Gateway Routing Protocol carry a default administrative distance of 90. This relatively low value positions EIGRP as more trustworthy than OSPF at 110, RIP at 120, and external EIGRP routes at 170, ensuring that routers prefer EIGRP paths when multiple dynamic routing protocols advertise routes to the same destination network prefix.

Question 356

Which IEEE standard defines Power over Ethernet (PoE), enabling switches to transmit electrical power alongside digital data over copper cables?

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

Correct Answer: 1

Explanation:

The IEEE 802.3af Power over Ethernet standard enables enterprise switches to transmit electrical power alongside digital data streams over standard twisted-pair copper Ethernet cables to power remote devices such as IP phones, wireless access points, and security cameras. The 802.3af standard specifies a maximum power delivery of 15.4 watts of DC power at the switch source port, delivering approximately 12.95 watts of usable power at the powered device after accounting for cable resistance losses. For higher-power equipment, the subsequent IEEE 802.3at (PoE+) standard increased power delivery capabilities up to 30.0 watts per port.

Question 357

What is the primary operational function of the service password-encryption global configuration command in Cisco IOS?

1. Encrypting all OSPF routing protocol update packets.
2. Obfuscating plain-text passwords stored within running and startup configuration files into type-7 hashes.
3. Enabling secure SSH remote management sessions on virtual terminal lines.
4. Generating cryptographic RSA keys for IPsec VPN tunnels.

Correct Answer: 2

Explanation:

The service password-encryption command is a global configuration command in Cisco IOS designed to enhance device security by obfuscating plain-text passwords stored within configuration files. By default, passwords configured for console lines, auxiliary lines, and virtual terminal login sessions are stored in clear text within configuration files, making them easily readable to anyone with viewing access. When enabled, Cisco IOS applies a reversible cryptographic algorithm to scramble these strings into type-7 encrypted hashes. While type-7 encryption is relatively weak, it successfully prevents casual observers from reading administrator passwords on screen or in configuration text backups.

Question 358

Which TCP control flag forces an immediate, unceremonious teardown of a session when an error or rejection occurs?

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

Correct Answer: 4

Explanation:

The Reset flag is an essential control flag utilized within the Transmission Control Protocol header to handle exceptional error conditions, invalid segments, or abrupt connection terminations. Unlike the graceful teardown managed by the FIN flag, the RST flag forces an immediate and unceremonious teardown of the TCP session. When a host receives a packet destined for a closed port or encounters a severe protocol violation, it transmits a segment with the RST flag set. Upon receiving this reset segment, the remote host immediately drops the connection, clears allocated socket memory, and aborts pending transmission queues without waiting for acknowledgments.

Question 359

Which TCP port is utilized by default for legacy, unencrypted Telnet remote command-line administration?

1. Port 21
2. Port 22
3. Port 23
4. Port 80

Correct Answer: 3

Explanation:

Telnet operates by default over Transmission Control Protocol port 23. Telnet is a legacy application layer protocol used to log into remote network devices and execute command-line instructions. Because Telnet transmits all keystrokes, passwords, and configuration commands in clear text across the network without encryption, it leaves network infrastructure highly vulnerable to packet sniffing and session hijacking attacks. Modern network administration standards mandate replacing Telnet with Secure Shell (SSH), which operates over TCP port 22 and encrypts the entire communication session from end to end to ensure robust confidentiality and integrity.

Question 360

Which Cisco IOS command displays the active Layer 3 routing table, including connected, static, and dynamically learned routes?

1. show running-config
2. show ip interface brief
3. show ip route
4. show version

Correct Answer: 3

Explanation:

The show ip route command is one of the most frequently executed diagnostic commands in the Cisco IOS command-line interface when operating in privileged EXEC mode. When invoked, it displays the router’s complete active Layer 3 routing table. The output details destination subnet prefixes, administrative distances, metric values, next-hop IP addresses, exit physical interfaces, and routing source codes (such as C for connected, S for static, O for OSPF, and D for EIGRP). Network administrators rely heavily on this command to verify route propagation, confirm routing protocols are populating paths correctly, and troubleshoot packet delivery failures.