A network administrator needs to assign IP addresses to a newly installed network. They choose 192.168.1.0 /24 as their network address and need to create three subnets with 30 hosts on each subnet. Which of the following is a valid subnet mask that will meet the requirements?
Correct Answer: C
Understanding the Requirements * Network Address: 192.168.1.0/24 * The /24 notation means a subnet mask of 255.255.255.0, providing 256 total addresses (192.168.1.0-192.168.1.255). * Usable hosts: 256 - 2 (network and broadcast) = 254. * Goal: Create3 subnets, each with30 hosts. * Each subnet needs enough addresses to accommodate 30 hosts, plus 2 reserved addresses (network and broadcast) per subnet. * Total addresses per subnet = 30 (hosts) + 2 (network/broadcast) =32 addresses. Subnetting Basics (Networking Fundamentals) * Subnet Mask: Determines how many bits are borrowed from the host portion to create subnets. * Original Mask: /24 (255.255.255.0) = 24 network bits, 8 host bits. * Formulae: * Number of subnets = 2^(number of borrowed bits). * Number of addresses per subnet = 2^(remaining host bits). * Usable hosts per subnet = 2^(remaining host bits) - 2. We need: * At least3 subnets. * At least32 addresses per subnet(to fit 30 hosts + 2 reserved). Step-by-Step Analysis * Determine Addresses Needed per Subnet: * 32 addresses is a power of 2 (2^5 = 32). * This means each subnet requires 5 host bits (since 2^5 = 32 total addresses, and 32 - 2 = 30 usable hosts). * Calculate Remaining Bits: * Original network has 8 host bits (/24). * If 5 bits are left for hosts, we borrow: 8 - 5 =3 bitsfor subnetting. * New Subnet Mask: * Original mask: /24 (24 network bits). * Borrow 3 bits: 24 + 3 =/27. * /27 = 255.255.255.224 (binary: 11111111.11111111.11111111.11100000). * Verify Requirements: * Number of Subnets: 2^3 =8 subnets(meets the requirement of at least 3). * Addresses per Subnet: 2^5 =32 addresses. * Usable Hosts per Subnet: 32 - 2 =30 hosts(exactly meets the requirement). * Subnet Breakdown: * Increment: 256 - 224 =32(each subnet increments by 32 in the fourth octet). * Subnets: * 192.168.1.0-192.168.1.31 (Network: .0, Broadcast: .31, Hosts: .1-.30) * 192.168.1.32-192.168.1.63 (Network: .32, Broadcast: .63, Hosts: .33-.62) * 192.168.1.64-192.168.1.95 (Network: .64, Broadcast: .95, Hosts: .65-.94) * (And 5 more subnets up to 192.168.1.255.) * Three subnets fit perfectly with 30 hosts each. Evaluating the Options * A. 255.255.255.128 (/25): * Borrow 1 bit: 24 + 1 = /25. * Subnets: 2^1 = 2 (not enough, need 3). * Host bits: 7 (2^7 = 128 addresses, 126 hosts). * Why Not: Only 2 subnets, fails the requirement. * B. 255.255.255.192 (/26): * Borrow 2 bits: 24 + 2 = /26. * Subnets: 2^2 = 4 (meets 3). * Host bits: 6 (2^6 = 64 addresses, 62 hosts). * Why Not: 62 hosts exceeds 30, but it's overkill; /27 is more efficient and still valid. * C. 255.255.255.224 (/27): * Borrow 3 bits: 24 + 3 = /27. * Subnets: 2^3 = 8 (meets 3). * Host bits: 5 (2^5 = 32 addresses, 30 hosts). * Why Yes: Perfectly fits 3 subnets with exactly 30 hosts each. * D. 255.255.255.240 (/28): * Borrow 4 bits: 24 + 4 = /28. * Subnets: 2^4 = 16 (meets 3). * Host bits: 4 (2^4 = 16 addresses, 14 hosts). * Why Not: Only 14 hosts per subnet, fails the 30-host requirement. Why /27 (255.255.255.224) is Best * It providesexactly 30 usable hosts per subnet, avoiding waste while meeting the minimum requirement. * It allows8 subnets, exceeding the need for 3, ensuring flexibility. * The study guide emphasizes efficient subnet design, and /27 balances host count and subnet availability. CompTIA Network+ Context * Networking Fundamentals: Subnetting is a core skill, requiring understanding of CIDR, binary conversion, and address allocation. * Example from Study Guide: Similar problems calculate subnet masks for specific host counts, reinforcing /27 as a common solution for ~30 hosts.
Question 252
A network engineer receives a vendor alert regarding a vulnerability in a router CPU. Which of the following should the engineer do to resolve the issue?
Correct Answer: A
* Understanding the Vulnerability: * Vulnerabilities in the router CPU can be exploited to cause performance degradation, unauthorized access, or other security issues. * Firmware Update: * Firmware Role:The firmware is low-level software that controls the hardware of a device. Updating the firmware can address vulnerabilities by providing patches and enhancements from the manufacturer. * Procedure:Download the latest firmware from the vendor's website, follow the manufacturer's instructions to apply the update, and verify that the update resolves the vulnerability. * Comparison with Other Options: * Replace the System Board:This is a costly and often unnecessary step if the issue can be resolved with a firmware update. * Patch the OS:Patching the OS is relevant for devices with a full operating system but not directly applicable to addressing a CPU vulnerability on a router. * Isolate the System:Temporarily isolating the system can mitigate immediate risk but does not resolve the underlying vulnerability. * Best Practice: * Regularly check for and apply firmware updates to ensure that network devices are protected against known vulnerabilities. References: * CompTIA Network+ study materials on network security and device management.
Question 253
Which of the following cloud service models most likely requires the greatest up-front expense by the customer when migrating a data center to the cloud?
Correct Answer: A
Infrastructure as a Service (IaaS) typically requires the greatest up-front expense by the customer when migrating a data center to the cloud. IaaS provides virtualized computing resources over the internet, where customers rent virtual machines, storage, and networks. The customer is responsible for managing the operating systems, applications, and data. This model often necessitates significant initial investment in planning, migration, and configuring the infrastructure. In contrast, Software as a Service (SaaS) and Platform as a Service (PaaS) models usually involve lower up-front costs because they offer more managed services.
Question 254
A network technician replaced an access layer switch and needs to reconfigure it to allow the connected devices to connect to the correct networks. INSTRUCTIONS Click on the appropriate port(s) on Switch 1 and Switch 3 to verify or reconfigure the correct settings: Ensure each device accesses only its correctly associated network. Disable all unused switchports. . Require fault-tolerant connections between the switches. . Only make necessary changes to complete the above requirements.
Correct Answer:
See the solution below in Explanation. Explanation: To provide a complete solution for configuring the access layer switches, let's proceed with the following steps: * Identify the correct VLANs for each device and port. * Enable necessary ports and disable unused ports. * Configure fault-tolerant connections between the switches. Port 1 Configuration (Uplink to Core Switch) * Status: Enabled * LACP: Enabled * Speed: 1000 * Duplex: Full * VLAN Configuration: Tagged for VLAN60, VLAN90, VLAN120, VLAN150, VLAN220 Port 2 Configuration (Uplink to Core Switch) * Status: Enabled * LACP: Enabled * Speed: 1000 * Duplex: Full * VLAN Configuration: Tagged for VLAN60, VLAN90, VLAN120, VLAN150, VLAN220 Port 3 Configuration (Server Connection) * Status: Enabled * LACP: Disabled * Speed: 1000 * Duplex: Full * VLAN Configuration: Untagged for VLAN90 (Servers) Port 4 Configuration (Server Connection) * Status: Enabled * LACP: Disabled * Speed: 1000 * Duplex: Full * VLAN Configuration: Untagged for VLAN90 (Servers) Port 5 Configuration (Wired Users and WLAN) * Status: Enabled * LACP: Enabled * Speed: 1000 * Duplex: Full * VLAN Configuration: Tagged for VLAN60, VLAN120, VLAN150 Port 6 Configuration (Wired Users and WLAN) * Status: Enabled * LACP: Enabled * Speed: 1000 * Duplex: Full * VLAN Configuration: Tagged for VLAN60, VLAN120, VLAN150 Port 7 Configuration (Voice and Wired Users) * Status: Enabled * LACP: Enabled * Speed: 1000 * Duplex: Full * VLAN Configuration: Tagged for VLAN60, VLAN90, VLAN120, VLAN220 Port 8 Configuration (Voice, Printers, and Wired Users) * Status: Enabled * LACP: Enabled * Speed: 1000 * Duplex: Full * VLAN Configuration: Tagged for VLAN60, VLAN90, VLAN120, VLAN220 Port 1 Configuration (Unused) * Status: Disabled * LACP: Disabled Port 2 Configuration (Unused) * Status: Disabled * LACP: Disabled Port 3 Configuration (Connection to Device) * Status: Enabled * LACP: Disabled * Speed: 1000 * Duplex: Full * VLAN Configuration: Untagged for VLAN1 (Default) Port 4 Configuration (Connection to Device) * Status: Enabled * LACP: Disabled * Speed: 1000 * Duplex: Full * VLAN Configuration: Untagged for VLAN1 (Default) Port 5 Configuration (Connection to Device) * Status: Enabled * LACP: Disabled * Speed: 1000 * Duplex: Full * VLAN Configuration: Untagged for VLAN1 (Default) Port 6 Configuration (Connection to Device) * Status: Enabled * LACP: Disabled * Speed: 1000 * Duplex: Full * VLAN Configuration: Untagged for VLAN1 (Default) Port 7 Configuration (Connection to Device) * Status: Enabled * LACP: Disabled * Speed: 1000 * Duplex: Full * VLAN Configuration: Untagged for VLAN1 (Default) * Ports 1 and 2 on Switch 1 are configured as trunk ports with VLAN tagging enabled for all necessary VLANs. * Ports 3 and 4 on Switch 1 are configured for server connections with VLAN 90 untagged. * Ports 5, 6, 7, and 8 on Switch 1 are configured for devices needing access to multiple VLANs. * Unused ports on Switch 3 are disabled. * Ports 3, 4, 5, 6, and 7 on Switch 3 are enabled for default VLAN1. * Core Switch Ports should be configured as needed for uplinks to Switch 1. * Ensure LACP is enabled for redundancy on trunk ports between switches. By following these configurations, each device will access only its correctly associated network, unused switch ports will be disabled, and fault-tolerant connections will be established between the switches.
Question 255
Which of the following steps of the troubleshooting methodology would most likely include checking through each level of the OSI model after the problem has been identified?
Correct Answer: D
Introduction to Troubleshooting Methodology: Network troubleshooting involves a systematic approach to identifying and resolving network issues. The CompTIA Network+ certification emphasizes a structured troubleshooting methodology. Troubleshooting Steps: Identify the problem: Gather information, identify symptoms, and question users. Establish a theory of probable cause: Consider possible reasons for the issue. Test the theory to determine cause: Validate the theory with tests. Establish a plan of action to resolve the problem and implement the solution: Create and execute a resolution plan. Verify functionality and implement preventive measures: Ensure the solution works and prevent recurrence. Verifying Functionality: After implementing a solution, verifying functionality ensures that the problem is fully resolved. This involves testing the network to confirm that it operates correctly. Checking through each level of the OSI model helps to ensure that all potential issues at different layers (physical, data link, network, transport, session, presentation, and application) are addressed. Explanation of the Options: A . Establish a theory: This step involves hypothesizing possible causes, not verifying functionality. B . Implement the solution: This step involves executing the resolution plan. C . Create a plan of action: This step involves planning the resolution, not verification. D . Verify functionality: This step involves comprehensive checks, including OSI model layers, to ensure the issue is fully resolved. Conclusion: Verifying functionality is a critical step in the troubleshooting process, ensuring that the network operates correctly after a solution is implemented. It involves thorough testing across all OSI model layers. Reference: CompTIA Network+ guide explaining the troubleshooting methodology and the importance of verifying functionality (see page Ref 9 Basic Configuration Commands).
