13.3.3 Address Resolution Quiz Answers. Networking Basics Module 13 quiz exam answers
1. What is one function of the ARP protocol?
- obtaining an IPv4 address automatically
- mapping a domain name to its IP address
- resolving an IPv4 address to a MAC address
- maintaining a table of domain names with their resolved IP addresses
Explanation: 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.
2. Which destination address is used in an ARP request frame?
- 0.0.0.0
- 255.255.255.255
- FFFF.FFFF.FFFF
- 127.0.0.1
- 01-00-5E-00-AA-23
Explanation: 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, FFFF.FFFF.FFFF.
3. Which statement describes the treatment of ARP requests on the local link?
- They must be forwarded by all routers on the local network.
- They are received and processed by every device on the local network.
- They are dropped by all switches on the local network.
- They are received and processed only by the target device.
Explanation: One of the negative issues with ARP requests is that they are sent as a broadcast. This means all devices on the local link must receive and process the request.
4. What important information is examined in the Ethernet frame header by a Layer 2 device in order to forward the data onward?
- source MAC address
- source IP address
- destination MAC address
- Ethernet type
- destination IP address
Explanation: The Layer 2 device, such as a switch, uses the destination MAC address to determine which path (interface or port) should be used to send the data onward to the destination device.
5. What are two functions of MAC addresses in a LAN? (Choose two.)
- to allow the transfer of frames from source to destination
- to determine which host has priority to transfer data
- to indicate the best path between separate networks
- to associate with a specific network IP address
- to uniquely identify a node on a network
Explanation: All Ethernet network devices have a unique Media Access Control (MAC) address that is burned into the network interface card (NIC). The MAC address is used to direct data from a particular device to a specific network destination.
6. Refer to the exhibit. PC1 issues an ARP request because it needs to send a packet to PC2. In this scenario, what will happen next?
- PC2 will send an ARP reply with the PC2 MAC address.
- RT1 will send an ARP reply with the RT1 Fa0/0 MAC address.
- RT1 will send an ARP reply with the PC2 MAC address.
- SW1 will send an ARP reply with the PC2 MAC address.
- SW1 will send an ARP reply with the SW1 Fa0/1 MAC address.
Explanation: When a network device wants to communicate with another device on the same network, it sends a broadcast ARP request. In this case, the request will contain the IP address of PC2. The destination device (PC2) sends an ARP reply with the PC2 MAC address.
7. What addresses are mapped by ARP?
- IPv4 address to a destination MAC address
- destination IPv4 address to the source MAC address
- destination IPv4 address to the destination host name
- destination MAC address to the source IPv4 address
Explanation: 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.
8. Refer to the exhibit. Switches Sw1 and Sw2 have MAC address tables that are populated with all the exhibited host MAC addresses. If host H1 sends a frame with destination address FFFF.FFFF.FFFF, what will be the result?
- Sw1 will discard the frame.
- Sw1 will flood the frame out all ports except the inbound port. The frame will be discarded by Sw2 but processed by host H2.
- Sw1 will flood the frame out all ports except the inbound port. The frame will be flooded by Sw2 but discarded by hosts H2, H3, and H4.
- Sw1 will flood the frame out all ports except the inbound port. The frame will be flooded by Sw2 and processed by hosts H2, H3, and H4.
9. Refer to the exhibit. Host A needs to send data to the server, but does not know its MAC address. When host A sends out an ARP request, what response will be in the ARP reply?
- 00:0C:00:B4:00:10
- 00:0C:00:B4:00:24
- 00:0D:00:B4:12:F3
- 00:0D:00:B4:99:AA
- 02:C8:00:7D:12:33
Explanation: When a host communicates to a device that is not on the same local IP network, it must send the packet to the default gateway. The default gateway for Host A is the Fa0/0 port on router RTA, which has the MAC address of 00:0C:00:B4:12:F3.
10. Open the PT Activity. Perform the tasks in the activity instructions and then answer the question.
When PC0 pings the web server, which MAC address is the source MAC address in the frame from R2 to the web server?
- 0001.43EA.3E03
- 0001.9756.6278
- 0001.C972.4201
- 0001.C972.4202
- 0002.16D6.A601
Explanation: In the segment between R2 and the web server, when R2 encapsulates a frame to be sent to the web server, R2 uses the MAC address of its interface that is directly connected to the segment, Fa0/1, as the source MAC.
11. What statement describes a characteristic of MAC addresses?
- They are the physical address of the NIC or interface.
- They are only routable within the private network.
- They are added as part of a Layer 3 PDU.
- They have a 32-bit binary value.
Explanation: Any vendor selling Ethernet devices must register with the IEEE to ensure the vendor is assigned a unique 24-bit code, which becomes the first 24 bits of the MAC address. The last 24 bits of the MAC address are generated per hardware device. This helps to ensure globally unique addresses for each Ethernet device.
12. Which two characteristics describe MAC addresses? (Choose two.)
- physical address assigned to the NIC
- identifies source and destination in Layer 2 header
- logical address assigned by DHCP
- used by routers to select the best path to a destination
Explanation: The MAC address is referred to as a physical address because it is assigned by the manufacturer to the NIC. MAC addresses are contained in the Layer 2 header. IP addresses are Layer 3 addresses and are logical addresses that are assigned either dynamically through DHCP or manually configured. Routers use destination IP addresses to choose the best path over which to forward the packets.