ARP tables are used to store mappings of IPv4 addresses to MAC addresses. When
a network device needs to forward a packet, the device knows only the IPv4 address. To deliver
the packet on an Ethernet network, a MAC address is needed. ARP resolves the MAC address
and stores it in an ARP table.
14. A PC is configured to obtain an IPv4 address automatically from network 192.168.1.0/24. The
network administrator issues the arp –a command and notices an entry of 192.168.1.255 ff-ff-ff-
ff-ff-ff. Which statement describes this entry?
The IPv4 address of 192.168.1.255 on the 192.168.1.0/24 network is the broadcast
address, which is statically mapped to ff-ff-ff-ff-ff-ff in the ARP table.
15. A cybersecurity analyst believes an attacker is spoofing the MAC address of the default gateway
to perform a man-in-the-middle attack. Which command should the analyst use to view the MAC
address a host is using to reach the default gateway?
A Layer 2 switch determines how to handle incoming frames by using its MAC
address table. When an incoming frame contains a destination MAC address that is not in the
table, the switch forwards the frame out all ports, except for the port on which it was received.
17. Which two ICMPv6 messages are used during the Ethernet MAC address resolution process?
The ARP process is used to complete the necessary mapping of IPv4 and MAC
addresses that are stored in the ARP table that is maintained by each node on a LAN. When the
destination device is not on the same network as the source device, the MAC address of the
Layer 3 device on the the source network is discovered and added to the ARP table of the source
19. What is one function of the ARP protocol?
A. Mapping a domain name to its IP address
B. Resolving an IPv4 address to a MAC address
C. Obtaining an IPv4 address automatically
D. Maintaining a table of domain names with their resolved IP addresses
The two main functions of the ARP protocol are to resolve an IPv4 address to a MAC address and to maintain an ARP table, which lists the resolved pairs of IPv4 address and MAC address. A device automatically obtains an IP address through DHCP. The functions of DNS include resolving (or mapping) a domain name with its IP address and maintaining a table for the domain name/IP pairs.
20. Which action is taken by a Layer 2 switch when it receives a Layer 2 broadcast frame?
A. It sends the frame to all ports except the port on which it received the frame.
B. It drops the frame.
C. It sends the frame to all ports.
D. It sends the frame to all ports that are registered to forward broadcasts.
ARP, or the Address Resolution Protocol, works by mapping the IPv4 address to a
destination MAC address. The host knows the destination IPv4 address and uses ARP to resolve
the corresponding destination MAC address.
22. When an IPv4 packet is sent to a host on a remote network, what information is provided by ARP?
A. The IPv4 address of the destination host
B. The IPv4 address of the default gateway
C. The MAC address of the switch port that connects to the sending host
D. The MAC address of the router interface closest to the sending host
When a host sends an IPv4 packet to a destination on a different network, the
Ethernet frame cannot be sent directly to the destination host because the host is not directly
reachable in the same network. The Ethernet frame must be sent to another device known as the
router or default gateway in order to forward the IPv4 packet. ARP is used to discover the MAC
address of the router (or default gateway) and use it as the destination MAC address in the frame
23. The ARP table in a switch maps which two types of address together?
ARP performs two functions:
1. To obtain a specific MAC address when an IP address is known, by broadcasting an ARP request
message to all devices on a particular Ethernet network
2. To use the gathered information to create a viewable table of IP address to MAC address
25. Which destination address is used in an ARP request frame?
The purpose of an ARP request is to find the MAC address of the destination host
on an Ethernet LAN. The ARP process sends a Layer 2 broadcast to all devices on the Ethernet
LAN. The frame contains the IP address of the destination and the broadcast MAC address,