Chapter 5 Exam Review

What are two potential network problems that can result from ARP operation? (Choose two.)

-On large networks with low bandwidth, multiple ARP broadcasts could cause data communication delays. -Network attackers could manipulate MAC address and IP address mappings in ARP messages with the intent of intercepting network traffic. *Large numbers of ARP broadcast messages could cause momentary data communications delays. Network attackers could manipulate MAC address and IP address mappings in ARP messages with the intent to intercept network traffic. ARP requests and replies cause entries to be made into the ARP table, not the MAC address table. ARP table overflows are very unlikely. Manually configuring static ARP associations is a way to prevent, not facilitate, ARP poisoning and MAC address spoofing. Multiple ARP replies resulting in the switch MAC address table containing entries that match the MAC addresses of connected nodes and are associated with the relevant switch port are required for normal switch frame forwarding operations. It is not an ARP caused network problem.*

Which two statements describe features or functions of the logical link control sublayer in Ethernet standards? (Choose two.)

-The data link layer uses LLC to communicate with the upper layers of the protocol suite. -Logical link control is implemented in software. *Logical link control is implemented in software and enables the data link layer to communicate with the upper layers of the protocol suite. Logical link control is specified in the IEEE 802.2 standard. IEEE 802.3 is a suite of standards that define the different Ethernet types. The MAC (Media Access Control) sublayer is responsible for the placement and retrieval of frames on and off the media. The MAC sublayer is also responsible for adding a header and a trailer to the network layer protocol data unit (PDU).*

Store-and-forward

-always stores the entire frame -checks the CRC before forwarding -checks the frame length before forwarding

Cut-Through

-may forward runt frames - begins fowarding when the destination address is received. *A cut-through switch can forward frames before receiving the destination address field, thus presenting less latency than a store-and-forward switch. Because the frame can begin to be forwarded before it is completely received, the switch may transmit a corrupt or runt frame. All forwarding methods require a Layer 2 switch to forward broadcast frames.*

What is a characteristic of port-based memory buffering?

Frames are buffered in queues linked to specific ports.

Which statement is true about MAC addresses?

The first three bytes are used by the vendor assigned OUI. *A MAC address is composed of 6 bytes. The first 3 bytes are used for vendor identification and the last 3 bytes must be assigned a unique value within the same OUI. MAC addresses are implemented in hardware. A NIC needs a MAC address to communicate over the LAN. The IEEE regulates the MAC addresses.*

Which statement describes the treatment of ARP requests on the local link?

They are received and processed by every device on the local network. *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.*