ICND1-105 Part I (ch1-5) Networking Fundamentals

dotted-decimal notation (DDN)

The format used for IP version 4 addresses, in which four decimal values are used, separated by periods (dots).

connection establishment

The process by which a connection-orientated protocol creates a connection. With TCP, a connection is established by a three-way transmission of TCP segments.

4.8 Which of the following are functions of a routing protocol? (Choose two answers.) a. Advertising known routers to neighboring routers, b. Learning routes for subnets directly connected to the router, c.Learning routes, and putting those routes into the routing table, for routes advertised to the router by its neighboring routers, d. Forwarding IP packets based on a packet's destination IP address

A and C. Routers do all the actions listed in all four answers; however, the routing protocol does the functions in the two listed answers. Independent of the routing protocol, a router learns routes for IP subnets and IP networks directly connected to its interfaces. Routers also forward (route) IP packets, but that process is called IP routing, or IP forwarding, and is an independent process compared to the work of a routing protocol.

network interface card (NIC)

A computer card, sometimes an expansion card and sometimes integrated into the motherboard of the computer, that provides the electronics and other functions to connect to a computer network. Today, most NICs are specifically Ethernet NICs, and most have an RJ-45 port, the most common type of Ethernet port.

Ethernet link

A generic term for any physical link between two Ethernet nodes, no matter what type of cabling is used.

Ethernet port

A generic term for the opening on the side of any Ehternet node, typically in an Ethernet NIC or LAN switch, into which an Ethernet cable can be connected.

networking model

A generic term referring to any set of protocols and standards collected into a comprehensive grouping that, when followed by the devices in a network, allows all the devices to communicate. Examples include TCP/IP and OSI.

protocol data unit (PDU)

A generic term referring to the header defined by some layer of a networking model, and the data encapsulated by the header (and possibly trailer) of that layer, but specifically not including any lower-layer headers and trailers.

router table

A list of routes in a router, with each route listing the destination subnet and mask , the router interface out which to forward packets destined to that subnet and as needed, the next-hop router's IP address.

wireless LAN

A local area network (LAN) that physically transmits bits using radio waves. The name "wireless" compares these LANs to more traditional "wired" LANs, which are LANs that use cables (which often have copper wires inside).

wired LAN

A local-area network (LAN) that physically transmits bits using cables, often the wires inside cables. A term for local-area networks that use cables, emphasizing the face that the LAN transmits data using wires (in cables) instead of wireless radio waves.

packet

A logical grouping of bytes that includes the network layer header and encapsulated data, but specifically does not include any headers trailers below the network layer.

100BASE-T

A name for the IEEE Fast Ethernet standard that uses two pair copper cabling, a speed of 100 Mbps, and a maximum cable length of 100 meters.

1000BASE-T

A name for the IEEE Gigabit Ethernet standard that uses four copper cabling, a speed of 1000 Mbps (1 Gbps), and a maximum cable length of 100 meters.

leased line

A serial communications circuit between two points, provided by some service provider, typically a telephone company (telco). Because the telco does not dell a physical cable between the tow endpoints, instead charging a monthly fee for the ability to send bits between the two sites, the service is considered to be a leased service.

Ethernet

A series LAN standards defined by the IEEE, originally invented by Xerox Corporation and developed jointly by Xerox, Intel, and Digital Equipment Corporation

routing protocol

A set of messages and processes with which routers can exchange information about routes to reach subnets in a particular network. Examples of routing protocols include the Enhanced Interior Gateway Routing Protocol (EIGRP), the Open Shortest Path First (OSPF) protocol, and the Routing Information Protocol (RIP).

MAC address

A standardized data link layer address that is required for every device that connects to a LAN. Ethernet MAC addresses are 6 bytes long and are controlled by the IEEE. Also known as a hardware address, a MAC layer address, and a physical address.

Ethernet over MPLS (EoMPLS)

A term referring specifically to how a service provider can create an Ethernet WAN service using an MPLS network. More general, a term referring to Ethernet WAN services.

frame

A term referring to a data link

Ethernet frame

A term referring to an Ethernet data link header and trailer , plus the data encapsulated between the header and trailer

serial interface

A type of interface on a router, used to connect to some types of WAN links, particularly leased lines and Frame Relay access links.

5.2. Which of the following are typical functions of TCP? (Choose four answers.) a. Flow control (windowing), b. Error recovery, c. Multiplexing using port numbers, d. Routing, e. Encryption, f. ordered data transfer

A, B, C, and F. IP, not TCP, defines routing. Many other protocols define encryption, but TCP does not. The correct answers simply list various TCP features.

4.5 Imagine a network with two routers that are connected with a point-to-point HDLC serial link. Each router has an Ethernet, with PC1 sharing the Ethernet with Router1 and PC2 sharing the Ethernet with Router2. When PC1 sends data to PC2, which of the following is true? a. Router1 strips the Ethernet header and trailer off the frame received from PC1, never to be used again. b. Router1 encapsulates the Ethernet frame inside an HDLC header and sends the frame to Router2, which extracts the Ethernet frame for forwarding to PC2., c. Router1 strips the Ethernet and trailer off the frame received from PC1, which is exactly re-created by Router2 before forwarding data to PC2., d. Router1 removes the Ethernet , IP, and TCP headres and rebuilds the appropriate headers before forwarding the packet to Router2.

A. PC1 will send an Ethernet frame to Router 1, with PC1's MAC address as the source address and Router 1's MAC address as the destination address. Router 1 will remove the encapsulated IP packet from that Ethernet frame, discarding the frame header and trailer. Router 1 will forward the IP packet by first encapsulating it inside an HDLC frame but rather the IP packet. Router 2 will de-encapsulate the IP packet from the HDLC frame and forward it onto the Ethernet LAN, adding a new Ethernet header and trailer, but this header will differ. It will list Router 2's MAC address as the source address and PC2's MAC address as the destination address.

8. Which OSI layer defines the standards for cabling connectors? a. Layer 1, b. Layer 2, c. Layer 3, d. Layer, e. Layer 5, 6, or 7

A. The OSI physical layer includes all standards that specify the shape of connectors, wiring in cabling, electrical details, and encoding that the electrical details, and encoding that the electrical signals use to encode bits over a cable.

crossover cable

An Ethernet cable that swaps the pair used for transmission on one device to a pair used for receiving on the device on the opposite end of the cable. In 10BASE-T and 100BASE-TX networks, this cable swaps the pair at 1,2 to pins 3, 6 on the other end of the cable, and the pair at pins 3, 6 to 1,2 as well

unicast IP address

An IP address that represents a single interface. In IPv4, these addresses come from the Class A, B, and C ranges.

IP packet

An IP header, followed by the data encapsulated after the IP header, but specifically not including any headers and trailers for layers below the network layer.

IP network

An IPv4 Class A, B, or C network; called a classful network because these networks are defined by the class rules for IPv4 addressing.

ping

An Internet Control Message Protocol (IMP) echo message and its reply; ping often is used in IP networks to test the reachability of a network device.

cable Internet

An Internet access technology that uses a cable TV (CATV) cable, normally used for video, to send and receive data.

4.7 Which of the following are true about a LAN-connected TCP/IP host and its IP routing (forwarding) choices? (Choose two answers.) a. The host always sends packets to its default gateway. b. The host sends packets to its default gateway if the destination IP address is in a different class of IP network than the host., c. The host sends packets to its default gateway if the destination IP address is in a different subnet than the host. d. The host sends packets to its default gateway if the destination IP address is in the same subnet as the host.

B and C. IPv4 host generally use basic two-branch logic. To send an IP packet to another host on the same IP network or subnet that is on the same LAN, the sender sends the packet to its default router (also called the default gateway).

3.5 Which of the following Internet access technologies, used to connect a site to an ISP, offers asymmetric speeds? (Choose two answers.) a. Leased lines, b. DSL, c. Cable Internet, d. BGP

B and C. Leased lines transmit data at the same speed in both directions, making them a symmetric service. DSL and cable Internet offer asymmetric speeds, with a faster downstream speed. BGP is a routing protocol and not an Internet access technology.

2.7 Which of the following are true about the format of Ethernet addresses? (Choose three answers.) a. Each manufacturer puts a unique OUI code into the first 2 bytes of the address., b. Each manufacturer puts a unique OUI code into the first 3 bytes of the address., c. Each manufacturer puts unique OUI code into the first half of the address. d. The part of the address that hold this manufacturer's code is called the MAC., e. The part of the address that hold this manufacturer's code has no specific name., f. The part of the address that holds this manufacturer's code has no specific name.

B, C, E. The pre-assigned universal MAC address, given to each Ethernet port when manufactured, breaks the address into two 3-byte halves. The first half is called the organizationally unique identifier (OUI), which the IEEE assigns to the company that builds the product as a unique hex number to be used only by that company.

4.2 Which of the following is a valid Class C IP address that can be assigned to a host? a. 1.1.1.1, b. 200.1.1.1, c. 128.128.128.128, d. 224.1.1.1

B. 224.1.1.1 is a Class D address.

2.3 Which of the following is true about Ethernet crossover cables for Fast Ethernet? a. Pins 1 and 2 are reversed on the other end of the cable., b. Pins 1 and 2 on one end of the cable connect to pins 3 and 6 on the other end of the cable., c. Pins 1 and 2 on one end of the cable connect to pins 3 and 4 on the other end of the cable., d. The cable can be up to 1000 meters long to cross over between buildings., e. None of the other answers is correct.

B. Crossover cables cross the wire at one node's transmit pin pair to the different pins used as the receive pins on the other device. For 10- and 100-Mbps Ethernet, the specific crossover cable wiring connects the pair at pins 1 and 2 on each end of the cable to pins 3 and 6 on the other end of the cable, respectively.

2.5 Which of the following is true about the CSMA/CD algorithm? a. The algorithm never allows collisions to occur., b. Collisions can happen, but the algorithm defines how the computers should notice a collision and how to recover. c. The algorithm works with only tow devices on the same Ethernet., d. None of the others answers is correct.

B. NICs (and switch ports) use carrier sense multiple sense multiple access with collision detection (CSMA/CD) algorithm to implement half-duplex logic. CSMA/CD attempts to avoid collisions, but it also notices when collisions do occur, with rules about how the Ethernet nodes should stop sending, wait, and try again later.

5.5 In the URI http://www.certskills.com/ICND1, which part identifies the web server? a. http, b. www.certskills.com, c. certskills.com, d. http://www.certskills.com, e. The file name .html includes the hostname.

B. Note that the hostname is all text between the // and the /. The text before the // identifies the application layer protocol; and the text after the / represents the name of the web page.

1.4 The process of TCP on one computer marking a TCP segment as segment 1, and the receiving computer then acknowledging the receipt of TCP segment 1 is an example of what? a. Data encapsulation, b. Same-layer interaction, c. Adjacent-layer interaction, d. OSI model e. All of theses answers

B. Same-layer interaction occurs on multiple computers. The functions defined by that layer typically need to be accomplished by multiple computers=for example, the sender setting a sequence number for a segment and the receiver acknowledging receipt of that segment. A single layer defines that process, but the implementation of that layer on multiple devices is required to accomplish the function.

3.3 Which of the following fields in the HDLC header used by Cisco routers does Cisco add, beyond the ISO standard HDLC? a. Flag, b. Type, c. Address, d. FCS

B. The standard HDLC header does not include a Type field, which identifies the type of packet encapsulated inside the HDLC frame.

3.4 Two router, R1 and R2, connect using Ethernet over MPLS service. The service provides point-to-point service between these two routers only, as a Layer 2 Ethernet service. Which of the following are the most likely to be true about this WAN? (Choose two answers.) a. R1 will connect to a physical Ethernet link, with the other end of the cable connected to R2., b. R1 will connect to physical Ethernet link, with the other end of the cable connected to a device at the WAN service provider point of presence., c. R1 will forward data-link frames to R2 using an HDLC header/trailer., d. R1 will forward data-link frames to R2 using an HDLC header/trailer.

B. and D. The physical installation uses a model in which each router uses a physical Ethernet link to connect to some SP device in an SP facility called a point of presence (Pop). The Ethernet link does not span from each customer device to the other. From a data-link perspective, both routers use the same Ethernet standard header and trailer used on LANs; HDLC does not matter on these Ethernet WAN links.

2.8 Which of the following terms describe Ethernet address that can be used to send one frame that is delivered to multiple devices on the LAN? (Choose two answers.) a. Burned-in address, b. Unicast address, c. Broadcast address d. Multicast address

C and D. Ethernet supports unicast addresses, which identify a single Ethernet node, and group addresses, which can be used to send one frame to multiple Ethernet nodes. The two types of group addresses are the //broadcast address and multicast address.//

5.6 Fred opens a web browser and connects to the www.certskills.com website. Which of the following are typically true about what happens between Fred's web browser and the web server? (Choose two answers.) a. Messages flowing toward the server use UDP destination port 80., b. Messages flowing from the server typically use RTP., c. Messages flowing to the client typically use a source TCP port number of 80., d. Messages flowing to the server typically use TCP.

C and D. Web traffic uses TCP as the transport protocol, with HTTP as the application protocol. As a result, the web server typically uses well-known TCP port 80, which is the well-known port for HTTP traffic. Messages flowing to the web server would have a destination TCP port of 80, and messages from the server would have a source TCP port of 80.

5.4 What do you call data that includes the Layer 4 protocol header, and data given to Layer 4 by the upper layers, not including any headers and trailers from Layers 1 to 3? (Choose two answers.) a. L3PDU, b. Chunk, c. Segment, d. Packet, e. Frame, f. L4PDU

C and F. The terms packet and L3PDU refer to the header plus data encapsulated by Layer 3. Frame and L2PDU refer to the header (and trailer), plus the data encapsulated by Layer 2. Segment and L4PDU refer to the header and data encapsulated by the transport layer protocol.

4.9 A company implements a TCP/IP network, with PC1 sitting on an Ethernet LAN. Which of the following protocols and features requires PC1 to learn information from some other server device? a. ARP, b. ping, c. DNS, d. None of theses answers is correct.

C. Address Resolution Protocol (ARP) does allow PC1 to learn information is not stored on a server. The *ping* command does let the user at PC1 learn whether packets can flow in the network, but it again does not use a server. With the Domain Name System (DNS), PC1 acts as a DNS client, relying on a DNS client, relying on a DNS server to respond with information about the IP addresses that match a given hostname.

3.2 Which of the following is an accurate speed at which a leased line can operate in the United States? a. 100 Mbps, b. 100 Kbps c.256 Kbps d. 6.4 Mbps

C. Leased lines can run at various preset speeds. The include multiples of 64 kbps, up through 24 times 64 kbps. The speeds can also be multiples of T1 speed (1.544 Mbps), up to 28 times that speed.

4.6 Which of the following does a router normally use when making a decision about routing TCP/IP packets? a. Destination MAC address, b. Source MAC address, c. Destination IP address, d. Source IP address, e. Destination MAC and IP addresses

C. Routers compare the packet's destination IP address to the router's IP routing table, making a match and using the forwarding instructions in the matched route to forward the IP packet.

5.3 Which of the following functions is performed by both TCP and UDP? a.Windowing , b. Error recovery, c. Multiplexing using port numbers, d. Routing, e. Encryption, f. Ordered data transfer

C. TCP, not UCP, performs windowing, error recovery, and ordered data transfer. Neither performs routing or encryption.

2.6 Which of the following is true about the Ethernet FCS field? a. Ethernet uses FCS for error recovery., b. It is 2 bytes long., c. It resides in the Ethernet trailer, not the Ethernet header., d. It is used for encryption.

C. The 4-byte Ethernet FCS field, found in the Ethernet trailer, allows the receiving nod to see what the sending node computed with a math formula that is a key part of the error-detection process. Note that Ethernet defines the process of detecting errors (error detection), but not error recovery.

1.7 Which OSI layer defines the functions of logical network-wide addressing routing? a. Layer 1, b. Layer 2, c. Layer 3, d. Layer 4, e. Layer 5, 6, or 7

C. The network layer concerns itself with delivery of data over the complete end-to-end path. That requires a way to identify each device, using addresses, and the addresses must be logical addresses that are therefore not tied to the physical details of the network.

2.2 Which of the following Ethernet standards defines Gigabit Ethernet over UTP cabling? a. 10GBASE-T, b. 100BASE-T, c. 1000BASE-T, d. None of the other answers is correct.

C. The number before the word BASE defines the speed, in megabits per second (Mbps). 1000 Mbps equals 1 gigabit per second (1 Gbps). The T in the suffix implies a twisted-pair or UTP cabling, so 1000BASE-T is the UTP-based Gigabit Ethernet standard name.

3.6 Fred has just added DSL service at his home, with a separate DSL modem and consumer-grade router with four Ethernet ports. Fred wants to use the same old phone he was using before the installation of DSL. Which is most likely try about the phone cabling and phone used with his new DSL installation? a. He uses the old phone, cabled to one of the router/switch device's Ethernet ports., b. He uses the old phone , cabled to the DSL modem's ports., c. He uses the old phone, cabled to an existing telephone port and not to any new device., d. The old phone must be replaced with a digital phone.

C. With DSL, the requirements on the phone's wiring are unchanged. The phone can connect to any working telephone jack, as if the DSL modem and router did not exist.

5.1 Which of the following header fields identify which TCP/IP application gets data received by the computer? (Choose two answers) a. Ethernet Type , b. SNAP Protocol Type, c. IP Protocol, d. TCP Port Number, e. UDP Port Number

D and E. Many headers include a field that identifies the next header that follows inside a message. Ethernet uses the Ethernet Type field, and the IP header uses the Protocol field. The TCP and UDP headers identify the application that should receive the data that follows the TCP or UDP header by using the port number field in the TCP and UDP headers, respectively.

4.4 PC1 and PC2 are on two different Ethernet LANs that are separated by an IP router. PC1's IP address is 10.1.1.1, and no subnetting is used. Which of the following addresses could be used for PC2? (Choose two answers.) a. 10.1.1.2, b.10.2.2.2, c. 10.200.200.1, d. 9.1.1.1, e.225.1.1.1, f. 1.1.1.1

D and F. Without any subnetting in use, all addresses in the same network as 10.1.1.1-all addresses in Class A network 10.0.0.0-must be on the same LAN. Addresses separated from that network by some router cannot be in network 10.0.0.0 So, the two correct answers are the only two answers that list a valid unicast IP address that is not in network 10.0.0.0.

1.1 Which of the following protocols are examples of TCP/IP transport layer protocols? a. ethernet, b. HTTP, c. IP, d. UDP, e.SMTP, f. TCP

D and F. of the remaining answers, Ethernet defines both physical and data link protocols, PPP is a data link protocol, IP is a network layer protocol, and SMTP and HTTP are application layer protocols.

DNS

Domain Name System. An application layer protocol used throughout the Internet for translating host names into associated IP addresses.

segment

In TCP, a term used to describe a TCP header and its encapsulated data (also called L4PDU). Also in TCP, the process of accepting layer and

segment

In TCP, a term used to describe a TCP header and its encapsulated data (also called an L4PDU). Also in TCP, the process of accepting a large chunk of data from the application layer and breaking it into smaller pieces that fit into TCP segments. In Ethernet, a segment is either a single Ethernet cable or a single collision domain (no matter now many cables are used).

IEEE

Insitute of Eletrical and Electronics Engineeers. A professional organization that develops communications and network standards, among other activities.

IPv4 address

Literally, the version of the Internet Protocol defined in an old RFC 791, standardized in 1980, and used as the basis of TCP/IP networks and the Internet for over 30 years.

de-encapsulation

On a computer that receives data over a network, the process in which the device interprets the lower-layer headers and, when finished with each header, removes the header, revealing the next-higher layer PDU.

default router (default gateway)

On an IP host, the IP address of some router to which the host sends packets when the packet's destination address is on a subnet other than the local subnet.

same-layer interaction

The communication between two networking devices for the purposes of the functions defined at a particular layer of a networking model, with that communication happening by using a header defined by that layer of the model. The two devices set values in the header, send the header and encapsulated data, with the receiving devices interpreting the header to decide what action to take.

adjacent-layer interaction

The general topic of how on one computer, two adjacent layers in a networking architectural model work together with lower layer providing services to the higher layer.

encapsulation

The placement of data from higher-layer protocol behind the header (and in some cases, between a header and trailer) of the next-lower-layer protocol. for example, an IP packet could be encapsulated in an Ethernet header and trailer before being sent over an Ethernet.

error detection

The process of discovering whether a data link frame was changed during transmission. This process typically uses a Frame Check Sequence (FCS) field in the data link trailer.

error recovery

The process of noticing when some transmitted data was not successfully received.

flow control

The process of regulating the amount of data sent by a sending computer toward a receiving computer. Several flow control mechanisms exist, including TCP flow control, which uses windowing.

subnetting

The process of subdividing a Class A, B, or C network into smaller groups called subnets.

Ethernet address

A 48-bit (6-byte) binary number, usually written as a 12-digit hexadecimal number, used to identify Ethernet nodes in an Ethernet network. Ethernet frame headers list a destination and source address field, used by the Ethernet devices to deliver Ethernet frames to the correct destination.

1.2 Which of the following protocols are examples of TCP/IP data link layer protocols? (Choose two answers.) a. Ethernet, b. HTTP, c. IP, d.UDP, e. SMTP, f. TCP, g. PPP

A and G. Of the remaining answers, IP is a network layer protocol, TCP and UDP are transport layer protocols, and SMTP and HTTP are application layer protocols.

Frame Check Sequence

A field in many data link trailers used as part of the error-detection process.

ordered data transfer

A networking function, included in TCP, in which the protocol defines how the sending host should number the data transmitted, defines how the receiving device should attempt to reorder the data if it arrives out of order, and specifies to discard the data if it cannot be delivered in order.

RJ-45

A popular type of cabling connector used for Ethernet cabling. It is similar to the RJ-11 connector used for telephone wiring in homes in the United States. RJ-45 allows the connection of eight wires.

forward acknowledgment

A process used by protocols that do error recovery, in which the number that acknowledges data lists the next data that should be sent, not the last data that was successfully received.

1.5 The process of a web server adding a TCP header to the contents of a web page, followed by adding an IP header and then adding a data link header and trailer, is an example of what? a. Data encapsulation, b. Same-layer interaction, c. OSI model, d. All of theses answers are correct.

A. Encapsulation is defined as the process of adding a header in front of data supplied by a higher layer (and possibly adding a trailer as well).

2.1 In the LAN for a small office, some user devices connect to the LAN using a cable, while others connect using wireless technology (and no cable). Which of the following is true regarding the use of Ethernet in this LAN? a. Only the devices that use cables are using Ethernet. b. Only the devices that use wireless are using Ethernet c. Both the devices using cables and those using wireless are using Ethernet. d. None of the devices are using Ethernet.

A. The IEEE defines Ethernet LAN standards, with standard names that begin with 802.3, all of which happen to use cabling. The IEEE also wireless LAN standards, with standard names that begin with 802.11, which are separate standards from Ethernet.

ARP

Address Resolution Protocol. An Internet protocol used to map an IP address to a MAC address. Defined win RFC 826.

2.4 Each answer lists two types of devices used in a 100BASE-T network. If these devices were connected with UTP Ethernet cables, which pairs would devices would require a straight-through cable? (choose three answers.) a. PC and router, b. PC and switch, c. Hub and switch, d. Router and hub, e. Wireless access point (Ethernet port) and switch

B, D, and E. Routers wireless access point Ethernet ports, and PC NIC's all send using pins 1 and 2, whereas hubs and LAN switches transmit on pins 3 and 6. Straight-through cables connect devices that use opposite pin pairs for sending, because the cable does not need to cross the pairs.

1.3 The process of HTTP asking TCP to send some data and making sure that it is received correctly is an example of what? a. Data encapsulation, b. Same-layer interaction, c. Adjacent-layer interaction, d. all of theses answers are correct.

B. Adjacent-layer interaction occurs on one computer, with two adjacent layers in the model. The higher layer provides the services to the next higher layer.

3.1 In the cabling for a leased line, which of the following typically connects to a four-wire provided by a telco? a. Router serial interface without internal CSU/DSU, b. CSU/DSU, c. Router serial interface with internal transceiver, d. Switch serial interface

B. The four-wire circuit cable supplied by the telco connects to the device acting as the CSU/DSU. That can be an external CSU/DSU or a CSU/DSU integrated into a router serial interface card. LAN switches do not have serial interfaces, and router serial interfaces do not have tranceivers.

1.6 Which of the following terms is used specifically to identify the entity created when encapsulating data inside data link layer headers and trailers? a. Data, b. Chunk, c. Segment, d. Frame, e. Packet

D. By convention, the term frame refers to the part of a network message that includes the data link header and trailer, with encapsulated data. The term packet omits the data link header and trailer, leaving the network layer header, leaving transport layer header and its encapsulated data.

DSL

Digital subscriber line. Public network technology that delivers high bandwidth over conventional telco local-loop copper wiring a t limited distances. Typically used as an Internet access technology, connecting a user to an ISP.

sliding windows

For protocols such as TCP that allow the receiving device to dictate the amount of data the sender can send before receiving an acknowledgement-a concept called a window- a reference to the fact that the mechanism to grant future windows is typically just a number that grows upward slowly after each acknowledgment, sliding upward.

unicast address

Generally, any address in networking that represents a single device or interface, instead of a group of address (as ould be represented by a multicast or broadcast address).

web server

Software, running on a computer, that stores web pages and sends those web pages to web clients (web browsers) that request the web pages.

IP subnet

Subdivisions of a Class A, B, or C network, as configured by a network administrator. Subnets allow a single Class A, B, or C network to be used instead of multiple networks, and still allow for a large number of groups of IP addresses, as is required for efficient IP routing.

10BASE-T

The 10-Mbps baseband Ethernet specification using two pairs of twisted-pair cabling (Categories 3, 4, or 5): One pair transmits data and the other recieves data. 10BASE-T, which is part of the IEEE 802.3 specification, had distance linit of approximately 100 m (328 feet) per segment.

hostname

The alphanumeric name of an IP host.

Gigabit Ethernet

The common name for all the IEEE standards that send data at 1 gigabit per second.

URI

Uniform Resource Identifier. The formal and correct term for the formatted text used to refer to objects in an IP network. This text is commonly called a URL or a web address. For example, http://www.certskills.com/blog is a URI that identifies the protocol (HTTP ), hostname (www.certskills.com), and web page (blog)

4.3 What is the assignable range of values for the first octet for Class A IP networks? a. 0 to 127, b. 0 to 126 , c. 1 to 127, d. 1 to 126, e. 128 to 191, f. 128 to 192

c. 1 to 127

4.1 Which of the following are functions of OSI Layer 3 protocols? (Choose two answers.) a. Logical addressing, b. Physical addressing, c. Path selection, d. Arbitration,. e. Error recovery

A and C. The network layer defines addressing, in contrast to physical addressing. The logical address structure allows easy grouping of addresses, which

broadcast address

Generally, any address that represents all devices, and can be used to send one message to all devices. In Ethernet, the MAC address of all binary 1s, or FFFF.FFFF.FFFF in hex. For IPv4, see subnet broadcast address.

HTTP

Hypertext Transfer Protocol. The protocol used by web browser and web servers to transfer files, such as text and graphic files.

straight-through cable

In Ethernet, a cable that connects the wire on pin1 on one end of the cable to pin1 on the other end of the cable, pin 2 on one end to pin2 on the other end , and so on.

port

In TCP and UDP, a number that is used to uniquely identify the application process that either sent (source port) or should receive (destination port) data. In LAN switching, another term for switch interface.

Fast Ethernet

the common name for all the IEEE standards that send data at 100 megabits per second.