* A MAC address is a unique identifier assigned to a network interface card (NIC) that allows it to communicate on a physical network layer, such as Ethernet1. An IP address is a logical identifier assigned to a device that allows it to communicate on a network layer, such as IP2.
* A technician can use different methods to find the IP address of a device if they know its MAC address.
Two of the most common methods are looking at the ARP table and the DHCP leases.
* The ARP table is a data structure that stores the mappings between IP addresses and MAC addresses on a device. ARP stands for Address Resolution Protocol, which is a network protocol that enables devices to discover the MAC address of another device based on its IP address3. The ARP table is populated by sending ARP requests and receiving ARP replies, or by using static ARP entries that are manually configured4.
* A technician can look at the ARP table of their own device or a nearby device, such as a router or a switch, to find the IP address of a device with a known MAC address. For example, on a Windows device, the technician can use the command arp -a to display the ARP table, and look for the entry that matches the MAC address. On a Cisco device, the technician can use the command show ip arp to display the ARP table, and look for the entry that matches the MAC address.
* The DHCP leases are the records of the IP addresses that are assigned by a DHCP server to DHCP clients. DHCP stands for Dynamic Host Configuration Protocol, which is a network protocol that enables devices to obtain IP addresses and other network configuration parameters automatically from a DHCP server. The DHCP leases contain information such as the IP address, the MAC address, the lease duration, and the expiration time of each DHCP client.
* A technician can look at the DHCP leases of the DHCP server that serves the network segment where the device with the known MAC address is connected. For example, on a Windows DHCP server, the technician can use the DHCP console to view the DHCP leases, and look for the entry that matches the MAC address. On a Cisco DHCP server, the technician can use the command show ip dhcp binding to view the DHCP leases, and look for the entry that matches the MAC address.
* The other options are incorrect for the following reasons:
* C. IP route table is a data structure that stores the routes to different network destinations on a device. It does not store the MAC addresses of the devices on the network.
* D. DNS cache is a data structure that stores the mappings between domain names and IP addresses on a device. DNS stands for Domain Name System, which is a network service that translates human-readable domain names into IP addresses. It does not store the MAC addresses of the devices on the network.
* E. MAC address table is a data structure that stores the mappings between MAC addresses and switch ports on a switch. It does not store the IP addresses of the devices on the network.
* F. STP topology is a network design that uses the Spanning Tree Protocol (STP) to prevent loops and create a loop-free logical topology on a switched network. It does not store the IP addresses or the MAC addresses of the devices on the network. References:
* 1: MAC address - Wikipedia
* 2: IP address - Wikipedia
* 3: Address Resolution Protocol - Wikipedia
* 4: How ARP Works
* : How to Use the Arp Command in Windows
* : show ip arp
* : Dynamic Host Configuration Protocol - Wikipedia
* : DHCP Lease
* : View DHCP Leases
* : show ip dhcp binding
* : Routing table - Wikipedia
* : Domain Name System - Wikipedia
* : DNS cache - Wikipedia
* : MAC address table - Wikipedia
* : Spanning Tree Protocol - Wikipedia