Which of the following is a network that covers a large geographical area and is made up of many smaller networks group of answer choices internet www WAN LAN?
LANs, WANs, and the Internet (1.2)Many different components are required to allow a network to provide services and resources. These various components work together to ensure that resources are delivered in an efficient manner to those requiring the services. Show Components of a Network (1.2.1, 1.2.1.1)The network infrastructure contains three categories of network components—devices, media, and services—as shown in Figure 1-6.
Figure 1-6 Components of the Network Infrastructure The path that a message takes from source to destination can be as simple as a single cable connecting one computer to another or as complex as a network that literally spans the globe. This network infrastructure is the platform that supports the network. It provides the stable and reliable channel over which our communications can occur. Devices (Figure 1-6a) and media (Figure 1-6b) are the physical elements, or hardware, of the network. Hardware is often the visible components of the network platform such as a laptop, PC, switch, router, wireless access point, or the cabling used to connect the devices. Occasionally, some components might not be so visible. In the case of wireless media, messages are transmitted using invisible radio frequency or infrared waves without requiring any physical connecting media. Network components are used to provide services and processes (Figure 1-6c). These are the communication programs, called software, that run on the networked devices. A network service provides information in response to a request. Services include many of the common network applications people use every day, like email-hosting services and web-hosting services. Processes provide the functionality that directs and moves the messages through the network. Processes are less obvious to us but are critical to the operation of networks. End Devices (1.2.1.2)The network devices that people are most familiar with are called end devices, or hosts. These devices form the interface between users and the underlying communication network. Some examples of end devices are
A host device is either the source or destination of a message transmitted over the network. To distinguish one host from another, each host on a network is identified by an address. When a host initiates communication, it uses the address of the destination host to specify where the message should be sent. Data originates with an end device, flows through the network, and arrives at an end device. Messages can take alternate routes through the network between end devices. Intermediary Network Devices (1.2.1.3)Intermediary devices interconnect end devices. These devices provide connectivity and work behind the scenes to ensure that data flows across the network. Intermediary devices connect the individual hosts to the network and can connect multiple individual networks to form an internetwork. Examples of intermediary network devices are
The management of data as it flows through the network is also a role of the intermediary devices. Intermediary devices direct the path of the data but do not generate or change the data content. These devices use the destination host address, in conjunction with information about the network interconnections, to determine the path that messages should take through the network. Processes running on the intermediary network devices perform these functions:
Network Media (1.2.1.4)Communication across a network is carried on a medium. The medium provides the channel over which the message travels from source to destination. Modern networks primarily use three types of media to interconnect devices and to provide the pathway over which data can be transmitted. As shown in Figure 1-7, these media are
The signal encoding that must occur for the message to be transmitted is different for each medium type. On metallic wires, the data is encoded into electrical impulses that match specific patterns. Fiber-optic transmissions rely on pulses of light, within either infrared or visible light ranges. In wireless transmission, patterns of electromagnetic waves depict the various bit values. Different types of network media have different features and benefits. Not all network media have the same characteristics and are appropriate for the same purpose. The criteria for choosing network media are
Network Representations (1.2.1.5)When conveying complex information such as displaying all the devices and media in a large internetwork, it is helpful to use visual representations. A diagram provides an easy way to understand the way the devices in a large network are connected. Such a diagram uses symbols to represent the different devices and connections that make up a network. This type of “picture” of a network is known as a topology diagram. Like any other language, the language of networking uses a common set of symbols to represent the different end devices, network devices, and media, as shown in Figure 1-8. The ability to recognize the logical representations of the physical networking components is critical to being able to visualize the organization and operation of a network. Throughout this course and labs, you will learn both how these devices operate and how to perform basic configuration tasks on these devices. In addition to these representations, specialized terminology is used when discussing how each of these devices and media connect to each other. Important terms to remember are
Topology Diagrams (1.2.1.6)Topology diagrams, as shown in Figure 1-9, are mandatory for anyone working with a network. They provide a visual map of how the network is connected. There are two types of topology diagrams:
LANs and WANs (1.2.2)Network infrastructures can vary greatly in terms of
For this reason, networks are often classified into various types based on a number of characteristics. Types of Networks (1.2.2.1)Figure 1-10 illustrates the two most common types of network infrastructures:
Other types of networks include
Local-Area Networks (1.2.2.2)Local-area networks (LAN) are a network infrastructure that spans a small geographical area. Specific features of LANs include
Wide-Area Networks (1.2.2.3)Wide-area networks (WAN) are a network infrastructure that spans a wide geographical area. WANs are typically managed by service providers (SP) or Internet service providers (ISP). Specific features of WANs include
The Internet (1.2.3, 1.2.3.1)Although there are benefits to using a LAN or WAN, most individuals need to communicate with a resource on another network, outside of the local network within the home, campus, or organization. This is done using the Internet. As shown in Figure 1-11, the Internet is a worldwide collection of interconnected networks (internetworks or internet for short), cooperating with each other to exchange information using common standards. Through telephone wires, fiber-optic cables, wireless transmissions, and satellite links, Internet users can exchange information in a variety of forms. The Internet is a conglomerate of networks and is not owned by any individual or group. Ensuring effective communication across this diverse infrastructure requires the application of consistent and commonly recognized technologies and standards as well as the cooperation of many network administration agencies. There are organizations that have been developed for the purpose of helping to maintain the structure and standardization of Internet protocols and processes. These organizations include the Internet Engineering Task Force (IETF), the Internet Corporation for Assigned Names and Numbers (ICANN), and the Internet Architecture Board (IAB), plus many others. Intranet and Extranet (1.2.3.2)There are two other terms that are similar to the term Internet:
Intranet is a term often used to refer to a private connection of LANs and WANs that belongs to an organization, and is designed to be accessible only by the organization’s members, employees, or others with authorization. Intranets are basically an internet that is usually only accessible from within the organization. Organizations can publish web pages on an intranet about internal events, health and safety policies, staff newsletters, and staff phone directories. For example, schools can have intranets that include information on class schedules, online curricula, and discussion forums. Intranets usually help eliminate paperwork and speed workflows. The intranet can be accessible to staff working outside of the organization by using secure connections to the internal network. An organization can use an extranet to provide secure and safe access to individuals who work for a different organization, but require company data. Examples of extranets include
Internet Access Technologies (1.2.4.1)There are many different ways to connect users and organizations to the Internet. Home users, teleworkers (remote workers), and small offices typically require a connection to an Internet service provider (ISP) to access the Internet. Connection options vary greatly between ISP and geographical location. However, popular choices include broadband cable, broadband digital subscriber line (DSL), wireless WANs, and mobile services. Organizations typically require access to other corporate sites and the Internet. Fast connections are required to support business services, including IP phones, video conferencing, and data center storage. Business-class interconnections are usually provided by service providers (SP). Popular business-class services include business DSL, leased lines, and Metro Ethernet. Connecting Remote Users to the Internet (1.2.4.2)Figure 1-13 illustrates some common connection options for small office and home office users, which include
Many homes and small offices are now being connected directly with fiber-optic cables. This enables an Internet service provider to provide higher bandwidth speeds and support more services such as Internet, phone, and TV. The choice of connection varies depending on geographical location and service provider availability. What are your options for connecting to the Internet? Connecting Businesses to the Internet (1.2.4.3)Corporate connection options differ from home user options. Businesses often require higher bandwidth, dedicated bandwidth, and managed services. Connection options available differ depending on the number of service providers located nearby. Figure 1-14 illustrates common connection options for organizations, which include
The choice of connection varies depending on geographical location and service provider availability.
Figure 1-14 Internet Connectivity Options for Businesses |