Flashcards on Chapter 2 –
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When a NIC is in "promiscuous" mode, it will process only the frames in which the destination MAC address matches its own MAC address.
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False
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Routers do not forward broadcast packets.
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True
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If a router receives a packet and it does not have an entry in its routing table for the destination network, it will send the packet to its default route, if configured.
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True
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The function of a repeater is to extend the range of an existing network.
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True
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You cannot connect a hub to another hub unless it has an uplink port.
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False
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When a frame is received, which component reads the source and destination MAC addresses, looks up the destination to determine where to send the frame, and forwards it out the correct port?
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switch
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Why would you need to use a repeater?
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You need to add a group of computers to your network, and the distance is too far for normal means of communication.
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Which of the following is NOT a function of a hub?
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transmits the signal to the correct port
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How does a switch "learn" MAC addresses?
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The switch reads each frame and makes a note of where each MAC address came from.
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Why is the use of a switch preferred over a hub?
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1) Devices on a hub have to share the available bandwidth, 2) Switches are intelligent; they read the frame and determine where to send it, 3) Switches can operate in full-duplex mode.
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What does a switch store in its switching table?
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the source MAC address of a frame and the port it was received on
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What is a packet called that is intended for only one individual computer?
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unicast
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Just as a switch keeps records of MAC addresses that it has learned, so does your computer. What protocol does your computer use to learn MAC addresses?
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ARP
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What does it usually mean when the activity light on a switch is blinking?
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It is communicating with the network.
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What component of the computer provides it with a MAC address?
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NIC
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A MAC address is composed of two 24-bit numbers. What does the first 24-bit number represent?
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It's the organizationally unique identifier for the manufacturer of the device.
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What command issued from the command prompt will show the route that a packet travels from the issuing computer to another computer?
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tracert
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What is the purpose of the default route?
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It's where the router sends all packets with destinations of which it has no knowledge.
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A wireless access point is most like which other network device, in that all computers send signals through it to communicate with other computers?
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hub
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When referring to network bandwidth, what is the basic unit of measurement?
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bits per second
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Before a computer can transmit data on a wireless network in some cases, it must send What type of signal to the AP?
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RTS
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The SSID is configured on which of the following so that it can be distinguished from other available wireless networks?
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access point
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What command would you issue from the command prompt to test whether your computer has connectivity to the network?
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ping
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Which of the following are features of a router? (Choose all that apply)
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connects LANs to one another, works with packets instead of frames
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What type of indicator lights would you find on a hub?
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network activity, link status, collision
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The “Locally Administered Address” can be used to override the burned-in __________ address.
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MAC
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In a computer's IP address settings, the _____________ gateway is the address of the router to which a computer sends all packets that are intended for networks outside of its own.
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default
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A __________ frame is a message that is intended to be processed by all devices on the LAN.
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broadcast
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The network ____________ is a measurement of the amount of data that can pass through a network in a certain period of time.
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bandwidth
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A switch operating in ___________ mode can send and receive data at the same time.
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full-duplex
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device that uses MAC addresses to determine the destination of frame
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switch
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device that connects LANs
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router
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device that connects a computer with the network medium
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network interface card
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device that only regenerates incoming signals
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repeater
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communication in which a device can send and receive signals but not at the same time
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half-duplex mode
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device that connects wireless computers
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access point
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device that connects multiple computers but regenerates signals out all ports
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hub
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amount of data that can be transferred on a network
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network bandwidth
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how devices connected to a hub use network bandwidth
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bandwidth sharing
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how devices connected to a switch use network bandwidth
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dedicated bandwidth
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Why is the NIC considered the "gatekeeper"?
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The NIC's responsibility is to examine every frame that is received and either allow it access to the computer or reject it. In order for the frame to be accepted, the destination MAC address must match the NIC's MAC address, or it is refused. There are two exceptions to this rule. If the destination MAC address is a broadcast, then the NIC accepts it. If the NIC is put in promiscuous mode, then it will accept all frames.
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What are the major differences between a hub and a switch?
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The major difference is that switches are intelligent. They examine each frame that they receive for the destination MAC address and then send the frame out the correct port for that address. A hub simply accepts a frame from one of its ports and then sends it out all ports. A switch also keeps a table of MAC addresses so that it knows where to send a frame. Because a switch can control where it sends a frame, devices that are connected to a switch can communicate at the same time, allowing each device to access the full network bandwidth. With a hub, only one device can transmit at a time so the bandwidth is shared among all connected devices. Also, because a switch controls the flow of frames, there is little chance of a collision. In a hub, collisions might occur frequently when under heavy use.
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List the steps that a switch performs for each frame.
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First, the switch receives a frame. It examines the frame for the source and destination MAC addresses. Then the switch looks up the destination MAC address in its switching table. In the switching table, the MAC address will be listed with the port number where the destination device can be found. The switch then will forward the frame out the appropriate port. The switch also updates its switching table with the source MAC address.
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What is a broadcast frame?
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A broadcast frame is a frame that has a destination MAC address of all binary 1s, which in hexadecimal notation reads as FF-FF-FF-FF-FF-FF. Broadcast frames carry messages that are intended for all devices on a network. Broadcast frames are forwarded by hubs and switches but not by routers.
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What is the difference between a switch and a router?
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Routers are used to connect LANs together. A switch is used to connect computers and other devices together to form a LAN. Routers are intelligent just like a switch, but routers deal with IP addresses instead of MAC addresses and packets instead of frames. Switches forward broadcast messages to all devices on a LAN, but routers separate LANs so they do not forward broadcast messages.
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What does a router keep in its routing table?
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Each interface of a router is a connection to a different network. The router needs to keep a record of the networks that are attached to it so that it can forward the packets it receives to the correct network. So, a routing table consists of a list of what network is available via which interface.
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What is the importance of a default route?
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When a router receives a packet, it looks at the destination IP address to determine where to send the packet. If the router has an entry for the network that the packet is intended for, then everything is fine, and it forwards the packet. However, if there is no entry in the routing table and no default route, then the router does not keep the packet; it simply discards it. If a default route is entered, then the router forwards the packet out the interface listed in the routing table so the packet is not discarded.
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What is a default gateway?
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A computer on a LAN can communicate with other devices on the same LAN because a switch uses the computer's physical address. However, when a computer wants to communicate with a device on another network, it must send the packet to the router so the computer needs to know the address of the router. The address of the router is considered the default gateway. It is where all packets sent from the computer to destinations other than its own network are sent. This address is included in a computer's IP configuration.
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What are the major tasks that a NIC performs?
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A NIC, along with its driver, provides your computer with a connection to the network medium. When a NIC receives a packet from the network protocol, it encapsulates the packet with the source and destination in a new header and the CRC in a trailer. Then it converts the frame into bits and sends it to the network medium. When the NIC receives a message, it does the reverse, converts the bits into a frame. Then the NIC checks the destination MAC to make sure that it is the same as its own or a broadcast address. It then removes the header and trailer and sends the packet on up to the network protocol.
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What is the MAC address of a computer?
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The MAC address is a number that is burned into the memory of each NIC. It is a unique number assigned by the manufacturer. It is 48 bits and is usually expressed in six two-digit hexadecimal numbers. The first 24 bits are an ID number for the manufacturer, called the OUI, and the last 24 bits are a serial number assigned by the manufacturer.
