The comparison and contrast between the 2 main reference models which uses the concept of protocol layering. Open System Interconnection Model (OSI) Transport Control Protocol /Internet Protocol (TCP/IP). Transmission Control Protocol (TCP) A connection-oriented transport protocol. Connection-oriented transport protocols provide reliable transport, in that if a segment is dropped, the sender can detect that drop and retransmit that dropped segment. Specifically, a receiver acknowledges segments that it receives. Based on those acknowledgments, a sender can determine which segments were successfully received. TCP operates at the transport layer of the OSI model.
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TCP three-way handshake.
1. It sends a message called a SYN to the target host.

2. The target host opens a connection for the request and sends back an acknowledgment message called an ACK (or SYN ACK).

3. The host that originated the request sends back another acknowledgment, saying that it has received the ACK message and that the session is ready to be used to transfer data.
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UDP
User Datagram Protocol A connectionless transport protocol. Connectionless transport protocols provide unreliable transport, in that if a segment is dropped, the sender is unaware of the drop, and no retransmission occurs.

UDP operates at the transport layer
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FTP
File Transfer Protocol (FTP)

Works at the Application layer

FTP provides for the uploading and downloading of files from a remote host running FTP server software. As well as uploading and downloading files, FTP enables you to view the contents of folders on an FTP server and rename and delete files and directories if you have the necessary permissions.

One of the big problems associated with FTP is that it is considered insecure. Even though simple authentication methods are associated with FTP, it is still susceptible to relatively simple hacking approaches. In addition, FTP transmits data between sender and receiver in an unencrypted format.
Identify the purpose, features, and functions of the following network components:
• Hubs
• Switches
• Bridges
• Routers
• Gateways
• CSU/DSU
• Network interface cards (NICs), ISDN adapters, and system area network cards
• Wireless access points (WAPs)
• Modems
A wide range of devices are used in modern networking. As a Network+ certified technician, you will need to have a good understanding of commonly used devices.
Given an example, identify a Media Access Control (MAC) address.
MAC addresses are the means by which systems communicate at a base level. As a network administrator, you will need to understand the purpose, function, and expression of MAC addresses.
Outline
• Introduction
• Hubs
• Switches
• Switching Methods
• Working with Hubs and Switches
• Hub and Switch Ports
• Cables Connecting Hubs and Switches
• Hub and Switch Indicator Lights
• Rack Mount, Stackable, and Freestanding Devices
• Managed Hubs and Switches
Typically, a local area network exists in a house or a university campus, while a wide area network exists over many office buildings separated by a vast distance. The office buildings in a WAN may be in different countries or even continents. For example, the headquarters may be in USA, the regional office may be in the UK, and the branch office may be in India. The workers in these three buildings use a Wide Area Network to collaborate with each other. The Internet can also be considered as a WAN, with the Ethernet being a classic example of WAN. Let us have a look at the two structures and their differences.

The Differences
In a LAN setup, devices are connected to a switch or a hub. Shared devices are also connected to a switch that is centrally located. In case the devices need to be connected to the Internet, the switch is then connected to the ISP and thus, to the Internet. The data that is shared amongst these devices is stored in servers. If more devices need to be added, an extra hub or switch can be added.

Local Area Network (LAN) has higher bandwidth, thus is faster when compared to a WAN. The maximum speed of a LAN can be 1000 megabits per second. As LAN is faster, it is widely preferred for sharing computers in a network. The network is easy to set up, most computers and laptops manufactured today come with the RJ45 port built-in on the motherboard, which is used to connect to the network. In case of older machines that do not have this port, a separate NIC (Network Interface Card) will be required to be installed. This card fits in the PCI slot on desktops, and the PCMCIA slot on laptops.

The main advantage of using LAN is the ease of sharing. Computers, if connected to the same LAN, can even share a printer. The biggest hurdle that a firm faces while connecting computers in a LAN is the monitoring of traffic for the Internet. If there is too much load put on only one computer or on a shared device, the network speed may reduce. This can be circumvented by using a LAN traffic monitor, whose function is to keep a track of the bandwidth used. On the basis of setup and maintenance cost breakup, LAN is considered to be cheaper as compared to a WAN setup.
Read more at Buzz. In a WAN setup, computers that are present at different locations are interconnected. The devices are connected to the router and the routers are interconnected via T1 standards. This makes it difficult to expand a WAN network.

Wide Area Network (WAN) has a lower bandwidth, thus slowing the network. The speed of a WAN can go up to 150 megabits per second. This means the speed of a WAN is one-tenth the speed of a LAN. Though WAN is slower, it is used widely to share data. The best example of WAN is the Internet. The data on the Internet is accessible across continents. However, a WAN cannot share computer peripherals, so a computer in one country cannot use a printer in another country. To set up a WAN, a modem and a router is needed. Thus, if an additional device needs to be added to the network, a router needs to be configured and connected to the others in the network. As the number of devices in a WAN are greater than those connected in a LAN, there is a greater need for a monitoring device. A special-purpose computer is used, whose only purpose is to send and receive data from the Internet. Leased lines or satellites are used to connect devices in a WAN.

While each of the two have their own advantages and disadvantages, there is also a distinct factor that helps one choose between a LAN and a WAN setup, and that is distance. If the locations to be connected are far apart, there is no point considering a LAN setup, as in spite of whatever advantages it may offer, it is not possible.
Network security is a broad topic with multi layered approach. It can be addressed at the data link layer, network layer and application layer. The issues concerned are: packet intrusion and encryption, IP packets and routing tables with their update version, and host-level bugs occurred at data link layer, network layer and application, respectively.
The TCP/IP protocols are being used globally irrespective of the nature of the organization whether it belongs to general category of organizations or security specific sensitive organizations. The news -:"information about hacking of some website or portal by some undesired people is very common nowadays. This shows that TCP/IP protocols are susceptible to intercept. This generated a need to ensure all round security for the network in an organization. The task of network administrator had to widen to inc1ude the overall security of the network. He has to ensure that all parts of this network are adequately protected and adequate measures of security have been implemented within a TCP/IP network. He should be aware of an effective security policy. He should also be able to pinpoint the main areas of risk that the network may face. Basically, these main areas of risk vary from network to network depending upon the organization functioning. There are, therefore, various security-related aspects which have direct implications for network administrator along with the means to monitor the implemented measures of security effectively arid to tackle the problem of breach of security if it happens.
Basic Requirements of Network Security
The main objective of the network is to share information among its users situated locally or remotely. Therefore, it is possible that undesired user can hack the network and can prove to be harmful for the health of the network or user. There are few basic points which must be followed by network administrator to provide the network an adequate security other than network-specific security as in case of e-commerce, etc. These are given below: