Module 9: Address Resolution

What is listed in a Packet header's "Type Field" that Identifies it as an ARP message?

0x806 Type indicates an ARP message

How are the IP addresses of the IP packets in a data flow associated with the MAC addresses on each link along the path to its destination for IPv4? IPv6?

1. ARP is used for IPv4 2. ICMPv6 Neighbor Discovery (ND) is used for IPv6

What does IPv6 Neighbor Discovery Protocol Provide (3)?

1. Address Resolution. 2. Router Discovery 3. Redirection Services All for IPv6 using ICMPv6

What are 2 security risks associated with using ARP?

1. Broadcast storms 2. ARP Spoofing/Poisoning

What 2 types of ICMPv6 messages are used for messaging between devices and routers for router discover?

1. ICMPv6 Router Solicitation (RS) 2. ICMPv6 Router Advertisement (RA)

What are three commands used to see a MAC address on a switch?

1. show arp 2. Show mac-address-table 3. Show interfaces

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 sends the frame to all ports that are registered to forward broadcasts. C. It sends the frame to all ports. D. It drops the frame.

A. It sends the frame to all ports except the port on which it received the frame. (Topic 9.2.0 - When a Layer 2 switch receives a frame with a broadcast destination address, it floods the frame to all ports except the port on which it received the frame.)

What protocol is used by IPv4 to associate the IPv4 address of a device with its MAC address?

ARP

What is an attack using ARP

ARP Poisoning

What two protocols are used to determine the MAC address of a known destination device IP address (IPv4 and IPv6)?

ARP, ND

What destination MAC address would be included in a frame sent from a source device to a destination device on the same local network? A. A broadcast MAC address of FF-FF-FF-FF-FF-FF B. MAC address of destination device C. MAC address of local router interface

B. MAC address of destination device

What are 2 functions provided by ARP? A. Maintains table of IPv4 addresses to domain names B. Maintains table of IPv4 to MAC address Mappings C. Maintains table of IPv6 to MAC address Mappings D. Resolves IPv4 addresses to domain names E. Resolves IPv4 addresses to MAC addresses F. Resolves IPv6 addresses to MAC Addresses

B. Maintains table of IPv4 to MAC address Mappings E. Resolves IPv4 addresses to MAC addresses

What type of addresses are used to send ICMPv6 neighbor solicitation messages? A. unicast B. multicast C. Broadcast

B. Multicast

Which destination addresss used in an ARP request frame? A. 0.0.0.0. B. 127.0.0.1 C FFFF.FFFF.FFFF D. 255.255.255.255

C FFFF.FFFF.FFFF (Topic 9.2.0 - 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.)

What destination MAC address would be included in a frame sent from a source device to a destination device on a remote local network? A. A broadcast MAC address of FF-FF-FF-FF-FF-FF B. MAC address of destination device C. MAC address of local router interface

C. MAC address of local router interface

Which router component holds the routing table, ARP cache, and running configuration file? A. ROM B. NVRAM C. RAM D. Flash

C. RAM (Topic 9.2.0 - The routing table, ARP cache, and running configuration file are stored in volatile RAM.)

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 can analyst use to view the MAC address a host is using to reach the default gateway? A. netstat -r B. ipconfig/all C. route print D. arp -a

D. arp -a (Topic 9.2.0 - ARP is a protocol used with IPv4 to map a MAC address to an associated specific IP address. The command arp -a will display the MAC address table on a Windows PC.)

Which type of ICMPv6 messages are used by routers for better next-hop selection?

ICMPv6 Redirect Messages

What does a Hub do with MAC and IP Addresses?

Nothing; Hub operates only at Layer 1

Where is ARP table stored on a device?

RAM

Where is the ARP table stored on a device?

RAM

Which 2 ICMPv6 messages are used in SLAAC?

Router Advertisement; Router Solicitation

When the destination IP address is on a remote network, what destination MAC address does the sending PC use?

The MAC address of the default gateway router.

What command is used on a Windows PC to view the ARP table?

arp -a

What command is used to clear the ARP Table?

arp -d

What are the five types of Neighbor Discovery (ND) messages used by ICMPv6 to perform address resolution, router discovery, and redirection services for IPv6?

1. Neighbor Solicitation Messages (NS) 2. Neighbor Advertisement Messages (NA) 3. Router Solicitation Messages (RS) 4. Router Advertisement Messages (RA) 5. Redirect Messages

What are the 2 types of addresses assigned to a device on an Ethernet LAN?

1. Physical Address (MAC Address) used for NIC to NIC communications on same Ethernet Network. 2. Logical Address (IP Address) used to send packet from source device to the destination device

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. What describes this entry? A. This is a Static Map Entry. B. This is a Dynamic Map Entry C. This entry maps to the default gateway D. This entry refers to PC itself.

A. This is a static map entry (Topic 9.2.0 - 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.)A.

How does the ARP process use an IPv4 address? A. To determine the MAC address of a device on the same network B. To determine the MAC address of the remote destination host C. To determine the amount of times a packet takes when traveling from source to destination. D. To determine the network number based on the number of bits in the IPv4 address

A. To determine the MAC address of a device on the same network (Topic 9.1.0 - 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 node.)

What will a Layer 2 Switch do when the destination MAC address of a received frame is not in the MAC table? A. It broadcasts the frame out to all ports on the switch B. it forwards the frame out of all ports except for the port at which the frame was received C. It initiates an ARP requesty D. It notifies the sending host that the frame can't be delivered

B. it forwards the frame out of all ports except for the port at which the frame was received (Topic 9.2.0 - 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.)

What is the purpose of ARP in an IPv4 network? A. To forward data onward based on the destination IP address. B. to obtain a specific MAC address when an IP address is known. C. to build the MAC address table in a switch from the info that is gathered. D. to forward data onward based on the destination MAC address.

B. to obtain a specific MAC address when an IP address is known. (Topic 9.2.0 - ARP performs two functions: 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 To use the gathered information to create a viewable table of IP address to MAC address mappings)

What type of information is contained in an ARP Table? A. switch ports associated with destination MAC addresses B. routes to reach destination networks C. domain name to IPv4 address mappings D. IPv4 address to MAC address mappings

D. IPv4 address to MAC address mappings (Topic 9.2.0 - 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.)

What addresses are mapped by ARP? A. Destination MAC address to the source IPv4 address B. Destination IPv4 address to the destination host name. C. Destination IPv4 address to the source MAC address D. IPv4 address to a destination MAC address.

D. IPv4 address to a destination MAC address. (Topic 9.2.0 - 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.)

The ARP table in a switch maps which two types of address together? A. Layer 4 address to a Layer 2 Address B. Layer 3 address to a Layer 4 address C. Layer 2 address to a Layer 4 address D. Layer 3 Address to a Layer 2 Address

D. Layer 3 Address to a Layer 2 Address (Topic 9.2.0 - The switch ARP table keeps a mapping of Layer 2 MAC addresses to Layer 3 IP addresses. These mappings can be learned by the switch dynamically through ARP or statically through manual configuration.)

What is one function of the ARP Protocol? A. Obtaining an IPv4 address automatically B. Maintaining a table of domain names with their resolved IP addresses C. Mapping a domain name to its IP address D. Resolving an IPv4 address to a MAC address

D. Resolving an IPv4 address to a MAC address (1. Topic 9.2.0 - 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.)

What command is used to display the ARP table on a Cisco Router?

show ip arp

What 2 ICMPv6 messages are used for MAC address resolution?

1. Neighbor Solicitation (NS) 2. Neighbor Advertisement (NA)

What are two types of ICMPv6 messages that are used for device-to-device messaging such as Address Resolution for IPv6 that is similar to ARP for IPv4?

1. Neighbor Solicitation (NS) 2. Neighbor Advertisement (NA) Both used for device-to-device messaging; devices included both host PCs and routers

What are 2 basic functions of ARP?

1. Resolves IPV4 addresses to MAC addresses 2. Maintains an ARP table of IPv4 to MAC address mappings.

Which 2 ICMPv6 messages are used during the Ethernet MAC address Resolution Process? (Choose 2) A. Neighbor Advertisement B. Neighbor Solicitation C. Echo Request D. Router Advertisement E. Router Solicitation

A. Neighbor Advertisement B. Neighbor Solicitation (Topic 9.3.0 - IPv6 uses neighbor solicitation (NS) and neighbor advertisement (NA) ICMPv6 messages for MAC address resolution.)

When an IPV4 packet is sent to a host on a remote network, what info is provided by ARP? A. the IPv4 address of the default gateway B. the MAC address of the switch port that connects to the sending host. C. the IPv4 address of the Destination Host D. The MAC address of the router interface closest to the sending host.

D. The MAC address of the router interface closest to the sending host. (Topic 9.1.0 - 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 header.)

What protocol is used by IPv6 to associate the IPv6 address of a device with its MAC address?

ICMPv6 is used by IPv6 to associate the IPv6 address of a device with the MAC address of the device NIC.

What protocol does IPv6 use to determine the MAC address of a device that has a known IPv6 address?

IPv6 Neighbor Discovery (ND) protocol

What type of address is FF-FF-FF-FF-FF-FF?

an ARP broadcast address

Which command can be used on a Cisco Router to view its ARP table?

show ip arp