The most plausible cause is an incorrect inter-VLAN routing configuration. This could manifest in several ways, such as missing or misconfigured VLAN interfaces (SVIs) on the Layer 3 switch. Each VLAN should have a corresponding SVI configured with an IP address that serves as the default gateway for devices in that VLAN. If the SVI for VLAN 20 is not configured or is incorrectly set up, devices in VLAN 10 will not be able to route packets to VLAN 20. The other options present potential issues but do not directly explain the connectivity problem. For instance, if the devices in VLAN 10 were using the wrong subnet mask, they would still be able to communicate with each other but might have issues reaching devices outside their subnet. Misconfigured switch ports for VLAN 20 as access ports would prevent devices in VLAN 20 from communicating with the switch, but it would not affect VLAN 10’s ability to communicate with VLAN 20. Lastly, if the devices in VLAN 20 were powered off, it would not explain the lack of routing capability; rather, it would simply mean that those devices are unreachable, but the routing path would still exist. Thus, the critical aspect of this troubleshooting scenario is to verify the inter-VLAN routing configuration on the Layer 3 switch to ensure that it is correctly set up to allow communication between VLANs 10 and 20. This involves checking the SVIs, ensuring that routing protocols (if used) are functioning correctly, and confirming that there are no access control lists (ACLs) blocking the traffic between these VLANs.

To resolve this, the administrator should first verify the configuration of the secondary DNS server, ensuring that it is operational and correctly set up to handle DNS queries. This includes checking network connectivity to the secondary DNS server and ensuring that it is configured to respond to requests appropriately. Additionally, the administrator should consider implementing a monitoring solution to track the availability of DNS servers and potentially configure a third DNS server for redundancy. Understanding the role of DNS in network connectivity is crucial; DNS servers translate human-readable domain names into IP addresses, allowing users to access websites and services. If both DNS servers are unreachable, users will not be able to resolve any domain names, leading to a complete loss of connectivity. Therefore, ensuring that at least one DNS server is reachable is vital for maintaining consistent network access. This situation highlights the importance of redundancy and proper configuration in network services to prevent downtime and ensure reliable connectivity.

In contrast, a single connection from each branch office to the data center would create a vulnerability; if that connection fails, the entire branch would lose access to critical resources. A flat network structure without VLANs would not only increase broadcast traffic but also complicate security and management, as different departments would not be isolated from each other. VLANs are essential for segmenting traffic based on departmental needs, enhancing both security and performance by reducing unnecessary broadcast domains. Lastly, while direct connections between all branch offices might seem beneficial for inter-office communication, this approach can lead to a complex and unmanageable network. It can also introduce additional points of failure and increase latency. Therefore, the most effective network diagram should clearly illustrate redundant connections and VLAN segmentation, ensuring both high availability and optimal performance across the enterprise network.

Regularly updating device firmware is equally crucial, as it addresses known vulnerabilities that could be exploited by attackers. Many IoT devices are shipped with outdated software, making them easy targets for cybercriminals. By ensuring that firmware is kept up-to-date, organizations can mitigate risks associated with unpatched vulnerabilities. In contrast, relying on default passwords is a common pitfall that can lead to unauthorized access, as many users neglect to change these passwords. Similarly, using a single firewall without network segmentation fails to provide adequate protection, as it does not isolate devices from one another, allowing potential threats to propagate across the network. Lastly, while disabling remote access may seem like a straightforward solution, it can hinder user convenience and functionality, leading to a poor user experience. In summary, a comprehensive security strategy for IoT devices should include strong authentication, regular firmware updates, and adherence to established security frameworks, ensuring both protection against unauthorized access and compliance with relevant regulations like GDPR.

In contrast, increasing the number of users with administrative privileges undermines the principle of least privilege, which is a fundamental concept in security practices. This could lead to a higher risk of data exposure, as more individuals would have the ability to access sensitive information without proper justification. Conducting a one-time security awareness training, while beneficial, is insufficient on its own. Continuous training and awareness programs are necessary to ensure that employees remain vigilant and informed about security practices and potential threats. Security awareness should be an ongoing effort rather than a singular event. Disabling all access controls temporarily is a highly risky action that could expose the organization to significant vulnerabilities. During maintenance or updates, it is crucial to maintain some level of access control to protect sensitive data from unauthorized access. Therefore, the most effective action for the organization to prioritize is the implementation of role-based access control (RBAC), as it directly addresses the compliance requirements of PCI DSS and significantly reduces the risk of unauthorized access to sensitive cardholder data. This approach not only aligns with regulatory standards but also fosters a culture of security within the organization, ensuring that access to critical systems is managed appropriately.

In contrast, cloud computing, while powerful for large-scale data storage and processing, introduces latency due to the time taken to send data to the cloud and receive responses. This delay can hinder the ability to respond quickly to changing traffic conditions. Traditional data warehousing is designed for historical data analysis and is not suited for real-time applications, as it typically involves batch processing of data rather than immediate insights. Batch processing, while useful for analyzing large datasets, does not provide the immediacy required for dynamic traffic management. The implementation of edge computing allows for localized data processing, which is crucial in scenarios where immediate action is necessary, such as adjusting traffic signals based on real-time traffic flow. This technology not only enhances the responsiveness of the traffic management system but also reduces the bandwidth required for data transmission to centralized servers, making it a more efficient solution for smart city applications. By leveraging edge computing, the municipality can achieve its goal of reducing traffic congestion effectively and efficiently.

The correct approach in this context is to assign specific permissions to each role—”Employee,” “Contractor,” and “Vendor”—based on their respective responsibilities and the principle of least privilege. This means that users will only have access to the resources necessary for their roles, minimizing the risk of unauthorized access to sensitive information. For instance, employees may have access to internal documents, while contractors might only access project-specific files, and vendors could be limited to certain data relevant to their services. The other options present flawed approaches to access control. Granting all users the same level of access disregards the principle of least privilege and increases the risk of data breaches. Assigning permissions based on seniority does not accurately reflect the actual job responsibilities and can lead to excessive access rights. Finally, granting access based solely on location ignores the critical aspect of role responsibilities, which is essential for effective access control. In summary, RBAC provides a structured and efficient way to manage user permissions, ensuring that access is granted based on defined roles that correlate with job functions, thereby enhancing security and compliance within the organization.

When these devices initiate connections to the internet, PAT translates their internal IP addresses to the single public IP address of 203.0.113.5. This translation is accomplished by assigning unique source port numbers to each session. The TCP/IP protocol allows for 65,536 possible port numbers (from 0 to 65,535). When a device from the internal network, say 192.168.1.10, initiates a connection to an external server, PAT will replace the source IP address with 203.0.113.5 and assign a unique source port number, for example, 50000. If another device, say 192.168.1.11, initiates its own connection, PAT will again use the same public IP address but will assign a different source port, such as 50001. This way, even though both devices are using the same public IP address, the unique source port numbers ensure that the return traffic can be correctly routed back to the originating device. The implications of this are significant: PAT allows for efficient use of a limited number of public IP addresses, enabling many devices to share a single address while maintaining distinct sessions. This is particularly useful in environments where public IP addresses are scarce or costly. Furthermore, the ability to handle multiple connections simultaneously is crucial for businesses that rely on internet access for various applications, including web browsing, email, and cloud services. In contrast, the other options present misconceptions about PAT. For instance, requiring each internal device to have a unique public IP address is impractical and defeats the purpose of using PAT. The claim that PAT can only handle a maximum of 64 connections is incorrect, as it can manage up to 65,536 simultaneous connections, limited only by the number of available port numbers. Lastly, the assertion that PAT does not support TCP connections is false; PAT is commonly used with TCP, UDP, and other protocols, making it versatile for various internet services.

Next, the engineer should verify the configuration of the physical interface to ensure it is set up for trunking if multiple VLANs are to be routed. If the physical interface is configured as an access port, it will only allow traffic for a single VLAN, which could explain why VLAN 20 is not receiving traffic. Additionally, checking the IP address configuration is crucial; if the IP address assigned to the VLAN 20 sub-interface is in a different subnet than the devices trying to communicate with it, this would also prevent traffic flow. Lastly, the engineer should confirm that the switch port connected to the router is configured correctly. If it is set as an access port rather than a trunk port, it will not allow traffic from VLAN 20 to pass through. Therefore, the engineer should ensure that the physical interface is configured to support trunking and that the sub-interfaces are correctly set up to handle the respective VLANs. This comprehensive approach to troubleshooting will help identify and resolve the issue effectively.

GDPR emphasizes the principle of data minimization, which means that individuals should only have access to the data necessary for their role. Similarly, HIPAA mandates that access to protected health information (PHI) must be restricted to authorized personnel only. By implementing RBAC, organizations can effectively manage user permissions, ensuring that employees can only access the data relevant to their job functions, thereby reducing the risk of data breaches. While the other options presented are important components of a security policy, they do not address the core requirement of access control as directly as RBAC does. A mandatory password change policy, while beneficial for security hygiene, does not inherently restrict access based on user roles. Annual security awareness training is essential for fostering a security-conscious culture but does not directly mitigate access risks. Lastly, while single sign-on (SSO) can enhance user convenience and potentially improve security by reducing password fatigue, it does not provide the same level of access control granularity as RBAC. In summary, prioritizing role-based access control in the security policy aligns with compliance requirements and effectively manages risks associated with unauthorized data access, making it a critical component of a robust security framework.

The formula for calculating the average is given by: \[ \text{Average} = \frac{\text{Total Attempts}}{\text{Total Hours}} \] Substituting the values into the formula: \[ \text{Average} = \frac{150}{24} \approx 6.25 \] This calculation indicates that, on average, there were approximately 6.25 unauthorized access attempts per hour from the specified IP address. Understanding log analysis tools is crucial for network security. These tools help in identifying patterns and anomalies in log data, which can indicate potential security threats. In this case, the high number of unauthorized access attempts from a single IP address could suggest a brute-force attack or a compromised account. Network administrators should also consider implementing additional security measures, such as rate limiting, IP blacklisting, or alerting mechanisms, to mitigate the risk of unauthorized access. Furthermore, analyzing logs over time can help in establishing baselines for normal behavior, making it easier to detect deviations that may indicate security incidents. In summary, the average number of unauthorized access attempts per hour is a critical metric that can inform security strategies and response actions. The correct calculation of this average is essential for effective log analysis and subsequent decision-making in network security management.

Moreover, the firewall’s role is to enforce security policies by allowing or denying traffic based on defined rules. If the application relies on both HTTP and HTTPS but also requires communication on other ports, the firewall must be configured to permit those additional ports. The other options present plausible scenarios but do not directly address the core issue. For instance, if the firewall were misconfigured to allow only outbound traffic, users would not be able to access the application at all, which contradicts the premise that they can access HTTP and HTTPS. Similarly, if the firewall were set to allow traffic only from specific IP addresses, it would likely result in a broader access issue rather than a specific application failure. Lastly, while blocking unencrypted HTTP requests could be a concern, it does not explain why the application would fail if HTTPS traffic is allowed. Thus, understanding the specific requirements of the application and ensuring that all necessary ports are open in the firewall configuration is crucial for maintaining seamless access to web applications. This highlights the importance of comprehensive documentation and analysis of application traffic patterns when configuring firewalls in a corporate environment.

The /64 subnet mask allows for a vast number of host addresses, specifically $2^{64}$, which equals 18,446,744,073,709,551,616 possible addresses. This is more than sufficient to accommodate 500 devices, as even a single /64 subnet can support an enormous number of hosts. If we consider the other options: – A /68 subnet would provide $2^{60}$ addresses, which equals 1,048,576 addresses. While this is also sufficient, it is not necessary since a /64 already meets the requirement. – A /70 subnet would yield $2^{54}$ addresses, which equals 16,384 addresses. This is still more than enough for 500 devices but is less efficient than using a /64. – A /72 subnet would provide $2^{56}$ addresses, which equals 65,536 addresses. Again, this is more than sufficient but does not align with best practices, as /72 subnets are generally not recommended for standard IPv6 addressing due to potential routing inefficiencies. In IPv6, it is a best practice to use /64 subnets for most networks, as this allows for the use of Stateless Address Autoconfiguration (SLAAC) and ensures compatibility with various IPv6 features. Therefore, the most efficient and practical choice for the administrator is to maintain the /64 subnet, which not only meets the current needs but also allows for future expansion without the need for reconfiguration.

The command `ip routing` is used to enable IPv4 routing on the router, but it does not affect IPv6 routing capabilities. It is essential to understand that IPv4 and IPv6 are distinct protocols, and enabling one does not automatically enable the other. The command `router ospf 1` is related to configuring the Open Shortest Path First (OSPF) routing protocol for IPv4. While OSPF can also be configured for IPv6 using OSPFv3, simply entering this command does not enable IPv6 routing on its own. Lastly, the option `ipv4 routing` is not a valid command in Cisco IOS. The correct terminology for enabling IPv4 routing is simply `ip routing`. In summary, to ensure that both IPv4 and IPv6 routing is operational on a Cisco router, the engineer must specifically enable IPv6 routing with the `ipv6 unicast-routing` command. This command is crucial for the router to recognize and process IPv6 traffic, thereby facilitating the coexistence of both IP versions in the network environment. Understanding the nuances of these commands is vital for effective network configuration and management, especially in modern networks that require dual-stack support for both IPv4 and IPv6.

By running the playbook in check mode, the engineer can identify any discrepancies between the current and desired configurations, allowing for informed decision-making before applying changes. This approach minimizes the risk of unintended disruptions in the network, as it provides a preview of the changes that would occur. In contrast, relying on a manual comparison (option b) is inefficient and prone to human error, while automatically applying configurations without checks (option c) can lead to significant issues if the current state is not as expected. Lastly, while version control systems are valuable for tracking changes, Ansible does not inherently include a built-in version control mechanism for configurations (option d). Instead, it focuses on idempotency, ensuring that running the same playbook multiple times results in the same state without unnecessary changes. Thus, understanding the role of check mode is crucial for effective network automation and configuration management.

Regulatory standards such as PCI DSS (Payment Card Industry Data Security Standard) and GDPR (General Data Protection Regulation) emphasize the importance of protecting sensitive data and responding promptly to security incidents. By isolating the systems, the institution not only adheres to these regulations but also demonstrates due diligence in protecting customer information. Blocking the external IP address without investigation (option b) may prevent immediate outbound connections but does not address the root cause of the issue. It could also lead to a false sense of security if the threat persists through other means. Notifying employees (option c) may raise awareness but does not directly mitigate the threat or provide actionable insights into the incident. Increasing the logging level (option d) could be beneficial for future monitoring but does not provide immediate remediation for the current situation. Thus, the most effective and compliant action is to isolate the affected systems and conduct a forensic analysis, ensuring that the institution can respond appropriately to the detected threat while maintaining regulatory compliance.

Given that the internal network is using the private IP address range of 192.168.1.0/24, this allows for 256 possible addresses (from 192.168.1.0 to 192.168.1.255), of which 254 are usable for devices (excluding the network and broadcast addresses). The requirement is for 50 devices to access the internet simultaneously, which is well within the capacity of a single public IP address, as NAT can handle multiple connections from different internal devices using the same public IP. The NAT device can maintain a unique mapping for each internal device’s connection to the public IP address. This means that as long as the NAT device can handle the number of simultaneous connections (in this case, 1024), only one public IP address is necessary to accommodate all 50 devices. Each device will have its own unique port number assigned by the NAT device, allowing it to distinguish between the different sessions. Thus, the minimum number of public IP addresses required for this NAT configuration is just one, as it can effectively manage the connections through port address translation (PAT). This highlights the efficiency of NAT in conserving public IP addresses while allowing multiple devices to connect to the internet.

The most plausible explanation for the RADIUS server not responding is that it is not configured to accept requests from the switch’s IP address. RADIUS servers typically have a list of authorized clients, which includes the IP addresses of the switches or access points that are allowed to send authentication requests. If the switch’s IP address is not included in this list, the RADIUS server will ignore the requests, leading to a lack of responses. While the other options present possible issues, they are less likely to be the root cause in this scenario. For instance, if the switch were not properly configured to use the correct EAP method, it would likely not send the authentication request at all, or it would result in a different type of failure. Similarly, if the user device were using an unsupported authentication protocol, the RADIUS server would typically respond with an error message rather than simply failing to respond. Lastly, while server overload can cause delays, it is less common for a server to completely stop responding to requests unless it is critically overloaded or misconfigured. Thus, ensuring that the RADIUS server is correctly configured to recognize and accept requests from the switch is essential for the successful implementation of 802.1X authentication in a network environment. This highlights the importance of proper configuration and understanding of the RADIUS server’s role in the authentication process.

The most plausible explanation for this behavior is that a firewall rule is blocking traffic to the server. Firewalls are commonly configured to restrict access to certain IP addresses or ports, especially in corporate environments where security is a priority. If the firewall is set to block ICMP (Internet Control Message Protocol) packets, which are used for pinging, the administrator would receive a timeout response even though the server is reachable from other networks. On the other hand, if the server’s IP address had changed recently, the administrator would likely not be able to ping it from any network, not just the local one. Similarly, if the local DNS server were not resolving the server’s hostname, the administrator would not be able to access the server using its hostname, but the ping test is specifically targeting the IP address. Lastly, while a faulty network cable could cause connectivity issues, it would typically result in a complete loss of connectivity rather than just a timeout response to a ping. Thus, the most logical conclusion is that a firewall rule is preventing access to the server, making it the most likely cause of the connectivity issue. This highlights the importance of understanding network security configurations and their impact on connectivity, as well as the need for a systematic approach to troubleshooting network issues.

In contrast, the other options either allow too much traffic or do not properly restrict access to the database server. For instance, option b incorrectly permits any TCP traffic to the database server, which could lead to unauthorized access. Option c allows all IP traffic to the database server after permitting MySQL traffic, which defeats the purpose of restricting access. Lastly, option d allows all IP traffic after permitting MySQL traffic, which also compromises security. Therefore, the correct configuration must prioritize specific permissions followed by a general denial to ensure that only authorized users can access the sensitive database server while blocking all other traffic. This approach aligns with best practices for implementing ACLs in network security, emphasizing the importance of a deny-all-by-default strategy to safeguard critical resources.

However, while mesh topology offers high availability and fault tolerance, it comes with increased complexity and cost. The installation and maintenance of a fully meshed network can be resource-intensive, as each node requires multiple connections. This can lead to higher cabling costs and more complex network management. In contrast, a star topology, while simpler and more cost-effective, introduces a single point of failure at the central hub. If the hub fails, the entire network goes down, which is not acceptable in high-availability environments. Similarly, a ring topology, where each node is connected in a circular fashion, can also suffer from a single point of failure; if one node goes down, it can disrupt the entire network unless additional measures, such as dual rings, are implemented. A hybrid topology, which combines elements of different topologies, can offer some advantages but may not provide the same level of fault tolerance as a full mesh. It can also introduce additional complexity in design and management. In summary, while mesh topology is the most suitable choice for ensuring high availability and fault tolerance in a corporate network, it is essential to weigh the benefits against the increased complexity and costs associated with its implementation. Understanding these trade-offs is crucial for network administrators when designing resilient network infrastructures.

When the Intern attempts to edit a financial record, the system must evaluate the permissions associated with the Intern role. Since the Intern’s role does not include the permission to edit, the system must enforce this restriction. The most appropriate response from the system is to deny the request outright, as allowing unauthorized access would violate the principles of least privilege and could lead to potential data integrity issues. Additionally, logging the attempt is crucial for auditing purposes, as it provides a record of unauthorized access attempts, which can be useful for security reviews and compliance audits. This scenario emphasizes the importance of strict adherence to access control policies and the need for systems to enforce these policies effectively. By denying the request and logging the attempt, the organization maintains control over sensitive data and ensures that only authorized personnel can perform actions that could affect the integrity of financial records. This approach not only protects the data but also reinforces the accountability of users within the system.

This structure allows for an enormous number of unique addresses within a single subnet—specifically, $2^{64}$ possible addresses, which equals 18,446,744,073,709,551,616 unique addresses. This vast address space is one of the key advantages of IPv6, enabling organizations to allocate addresses without the fear of exhaustion that is prevalent in IPv4. The incorrect options highlight common misconceptions about IPv6 addressing. For instance, the second option incorrectly states that the entire 128-bit address is used for the network prefix, which would severely limit the number of devices that could be addressed. The third option misrepresents the segmentation of the address, as IPv6 does not divide addresses into 32-bit segments for subnetting purposes. Lastly, the fourth option incorrectly claims that the last 64 bits are reserved for multicast addresses; in reality, they are primarily used for interface identifiers, allowing for unicast communication among devices in the subnet. Understanding these structural components is crucial for effective network design and management in an IPv6 environment.

On the other hand, configuring OSPF in the branch office (option b) may introduce unnecessary complexity. OSPF is designed for larger networks with multiple routers and dynamic route changes. In this case, the branch office’s single router does not require the dynamic capabilities of OSPF, which would add complexity and require additional configuration and maintenance. Using a combination of static and dynamic routing (option c) could lead to confusion and mismanagement, especially in a small network where static routes are sufficient. It could also complicate troubleshooting efforts, as the engineer would need to manage both static and dynamic routes. Relying solely on default routes (option d) is not advisable in this context, as it may lead to suboptimal routing decisions and potential connectivity issues. Default routes are useful in certain scenarios, but they do not provide the granularity needed for effective routing in a network that connects to a main office. In summary, static routing is the most appropriate choice for the branch office due to its simplicity, efficiency, and suitability for the network’s current size and complexity. This choice allows for easier management and better performance without the overhead associated with dynamic routing protocols.

Misconfigured VLANs can lead to devices being placed in the wrong broadcast domains, causing communication failures. Additionally, examining the switch logs can reveal error messages or alerts that indicate specific issues, such as port flapping or excessive errors on particular interfaces. While analyzing physical cabling is important, it is often a secondary step after confirming that the switch configurations are correct. Monitoring network traffic is also a valuable step, but it typically follows the initial configuration checks, as traffic anomalies may not be present if the configuration is incorrect. Conducting a user survey can provide insights into the symptoms but does not directly address the technical aspects of the network configuration that are likely causing the issues. Thus, prioritizing the review of switch port configurations is crucial for an effective root cause analysis, as it directly addresses potential misconfigurations that could lead to the connectivity problems experienced by users. This approach aligns with best practices in network troubleshooting, emphasizing the importance of configuration verification before moving on to other potential causes.

When the Developer attempts to access financial data, the RBAC system evaluates the permissions associated with the Developer role. Since accessing financial data is not included in the permissions for this role, the access control system will deny the request. This is a fundamental principle of RBAC, which emphasizes the principle of least privilege, ensuring that users only have access to the information necessary for their job functions. Furthermore, the RBAC model is designed to prevent unauthorized access and protect sensitive information, such as financial data, from being accessed by individuals who do not have the appropriate role. This ensures compliance with various regulations and guidelines, such as the General Data Protection Regulation (GDPR) and the Health Insurance Portability and Accountability Act (HIPAA), which mandate strict access controls to sensitive data. In summary, the outcome of the Developer’s attempt to access financial data will be a denial of access, reinforcing the importance of correctly implementing access control measures to safeguard organizational resources.

Additionally, using DNS round-robin allows for the distribution of incoming traffic across multiple server instances. This not only balances the load but also provides redundancy; if one server goes down, others can still handle requests, ensuring high availability. In contrast, relying solely on HTTP/2 without caching or a single DNS entry would not effectively manage high traffic, as it does not provide the necessary scalability or redundancy. Similarly, setting up a dedicated FTP server does not contribute to web server performance and is irrelevant to the HTTP traffic management. Lastly, using DHCP for a web server is not advisable, as it introduces unpredictability in IP address assignment, which can complicate DNS resolution and lead to accessibility issues. Thus, the combination of a CDN and DNS round-robin is the most effective approach for ensuring that the web server can handle high volumes of traffic while maintaining fast response times, making it the optimal choice for the scenario described.

Implementing TCP window scaling is particularly effective in high-latency environments or when dealing with high-bandwidth connections. By increasing the TCP window size, the amount of data that can be in transit before an acknowledgment is required is expanded, which can significantly reduce the number of round trips needed for data transmission. This is especially beneficial during peak hours when the network is congested, as it allows for more efficient use of available bandwidth. On the other hand, reducing the MTU size may lead to increased fragmentation, which can further exacerbate latency issues rather than alleviate them. Switching from TCP to UDP, while it may reduce overhead, sacrifices reliability and order of packet delivery, which is often unacceptable for web applications that require consistent data integrity. Lastly, increasing the timeout value for TCP connections could lead to longer delays in detecting lost packets, which can worsen performance rather than improve it. Thus, the most effective action to take in this scenario is to implement TCP window scaling, as it directly addresses the limitations of the TCP layer in handling data flow and can lead to a noticeable improvement in application performance during peak usage times.

In this scenario, the destination for a default route is represented by the IP address `0.0.0.0`, which signifies that this route will be used for any destination not explicitly defined in the routing table. The subnet mask for a default route is also `0.0.0.0`, indicating that it applies to all possible addresses. The next hop, in this case, is the IP address of the gateway, which is `192.168.1.254`. The command `ip route 0.0.0.0 0.0.0.0 192.168.1.254` correctly sets up the default route, directing any traffic that does not match a more specific route to the specified gateway. The other options present common misconceptions or incorrect configurations. For instance, option b specifies a route to a specific subnet (192.168.1.0) rather than a default route, which would not serve the purpose of directing traffic for unknown destinations. Option c incorrectly attempts to set a route with the gateway as the destination, which does not conform to the routing command syntax. Lastly, option d mistakenly sets the default route to the router’s own IP address, which would not be functional for forwarding unknown traffic. Understanding how to configure default routes is crucial for effective network management, especially in larger networks where multiple subnets are present. Default routes help streamline traffic flow and ensure that packets can be forwarded even when specific routes are not defined, thereby enhancing the overall efficiency of the network.

1. **Traffic Sensor**: This device sends data every 5 seconds. In one hour, which is 3600 seconds, the number of packets sent can be calculated as follows: \[ \text{Packets from Traffic Sensor} = \frac{3600 \text{ seconds}}{5 \text{ seconds/packet}} = 720 \text{ packets} \] 2. **Energy Meter**: This device sends data every 10 seconds. Similarly, we calculate the number of packets sent by the energy meter: \[ \text{Packets from Energy Meter} = \frac{3600 \text{ seconds}}{10 \text{ seconds/packet}} = 360 \text{ packets} \] 3. **Total Packets**: Now, we add the packets from both devices to find the total number of packets sent to the cloud in one hour: \[ \text{Total Packets} = 720 \text{ packets (Traffic Sensor)} + 360 \text{ packets (Energy Meter)} = 1080 \text{ packets} \] However, the question asks for the total number of packets sent in one hour from both devices combined, which requires us to consider the frequency of data transmission. The traffic sensor sends data more frequently, thus generating a higher volume of packets over the same period. To clarify, if we consider the total number of packets sent by both devices over the hour, we must also account for the overlap in their transmission intervals. The least common multiple (LCM) of their transmission intervals (5 seconds and 10 seconds) is 10 seconds. Therefore, in one hour (3600 seconds), the number of intervals is: \[ \text{Number of intervals} = \frac{3600 \text{ seconds}}{10 \text{ seconds}} = 360 \text{ intervals} \] In each interval, the traffic sensor sends 2 packets (every 5 seconds) and the energy meter sends 1 packet (every 10 seconds). Thus, the total packets sent in each interval is: \[ \text{Packets per interval} = 2 + 1 = 3 \text{ packets} \] Finally, the total number of packets sent in one hour is: \[ \text{Total Packets} = 360 \text{ intervals} \times 3 \text{ packets/interval} = 1080 \text{ packets} \] This calculation illustrates the importance of understanding both the frequency of data transmission and the interaction between different IoT devices in a network. The correct answer reflects a nuanced understanding of how IoT devices operate within a smart city architecture, emphasizing the need for effective data management and communication protocols.