Routing and Switching

The best tool to use for verifying the current routing path between two locations would be 'traceroute'. This tool allows the administrator to trace the route that packets take to reach the specified destination. It provides information on each hop along the path, including latency times, thereby helping to identify if traffic is taking a less efficient route. 'Ping' would only be used to determine if the destination is reachable and to measure round-trip time for messages sent from the originating host, but it wouldn't detail the path taken. 'Nslookup' resolves queries related to the Domain Name System (DNS) and it's not useful for verifying network paths. Lastly, 'route' is a Linux tool that allows system administrators to configure and modify the IP routing table, but it doesn't detail the path between two network points. Therefore, 'traceroute' is the most suitable tool in this scenario.

A network administrator wants to increase fault tolerance on the company's LAN and prevent network loops. The Spanning Tree Protocol (STP) is the best choice because it was specifically designed to prevent loop situations in a network. It allows a network design to include spare (redundant) links to provide automatic backup paths if an active link fails, without the danger of loops. By contrast, VLAN Trunking Protocol (VTP) is used to manage all configured VLANs across a switched internetwork. It's not aimed at addressing the network loops or providing fault tolerance. IEEE 802.1Q is the networking standard that supports virtual LANs (VLANs) on an Ethernet network, but it has no built-in mechanism to prevent network loops. Port Channel bundles multiple physical links to create a logical link to provide fault tolerance and high speed links between switches, routers, and servers, but does not have inherent loop prevention.

The correct parameter to modify in OSPF to establish a preferred route for traffic between the central office and a remote location is 'Cost'. The OSPF routing protocol uses 'Cost' as its metric, also known as the path cost, which determines the best path for data transfer. The path with the lowest cost is considered the best path and thus chosen for data transmission. Therefore, by adjusting the cost, the network administrator can influence which route OSPF uses as the preferred route. The other parameters such as 'Hello interval', 'Dead interval', and 'Hold time' are incorrect because they are not used to establish a preferred route. The 'Hello interval' is the time between the OSPF Hello packets that a router sends on an interface, not related to path selection. The 'Dead interval' is the time that a router will wait to hear from another router before declaring it down; it is also not related to path selection. The 'Hold time' is not even an OSPF parameter.