# Chapter 13 Journal

### Guiding questions&#x20;

#### How would you classify Champlain's network (for example, is it a PAN, LAN, or WAN)? Justify your answer.

Champlain college would utilize a CAN, campus area network which connects multiple LANs over a college campus. CANs typically are managed by the campus which uses it. WANs typically combine infrastructure managed by different organizations. CANs have lower latency as well with internal data transferring. &#x20;

#### Between the OSI and TCP/IP Model, which one seems more useful for describing networks? Justify your answer.

TCP/IP model is more useful for describing a network. It explains how different protocols at different levels work together to provide the functionality for the internet.&#x20;

#### Suppose Champlain College was given a Class A network ID for its network (i.e., it had 224 addresses to assign to computers). Give one reason why this would be a good thing, and one reason why this might be a bad thing.

The first major reason why this would be negative is it limits the network to 224 devices. However, it is positive because the 224 devices within the network would be able to communicate with each other without the need of a router.&#x20;

#### Suppose a colleague came to you and said that they could not connect to a website. How might you use some or all of the network tools from this chapter to diagnose the problem?

You would first want to check their connection with ifconfig. If they were connected to the internet via ethernet or wifi and had properly assigned IP you would want to see if anyone else was having the same problem. You would also want to ping the host website to confirm it is up and accepting connections. You may want to use nslookup to make sure the website is being hosted with the proper DNS address. If not you would try connecting to the ip address directly. If multiple people on the same network are having trouble then tracert would be used to find the problem within the LAN.&#x20;

### Networking Overview

A network is two or more devices which talk to each other and share resources. Networks allow users to share files, use network devices, and utilize the internet.

### Network Topologies

Network topology is how a network is physically wired. Popular topologies include star, extended star, hierarchy, ring, bus, and mesh topology.

### The OSI Model

The OSI model consists of 7 different layers. Level 1 is physical, level 2 is data link, level 3 is network, level 4 is transport, level 5 is session, level 6 is presentation, and level 7 is the application layer. Each layer of the OSI model uses the layer below. For example, the data link layer cannot be accessed without first going through the physical layer.

### The TCP/IP Model

The TCP/IP transport protocol is the protocol that the internet utilizes. It consists of 4 different layers application, transport, internet, and network access.&#x20;

* Application - The application layer is the highest abstraction layer of the TCP/IP model that provides the interfaces and protocols needed by the users.
* Transport - Adds port numbers in the header allowing the device to identify which application sent the data. It also allows a device to determine where to display the data. TCP and UDP are both transport protocols.
* Internet - IP is the most common internet layer protocol. This allows devices to know where certain data is hosted on the internet. It is also how applications know where to send data to users.&#x20;
* Network access - Defines how to format data for the type of network being used. It allows data to be brought to a network and MAC addresses are used to route data to the right device within the network.

### Network Addressing

An IP address is a unique identifier that allows devices to connect to certain websites or applications on the internet. It also allows data to be sent back to device for example video streaming. IP addresses are not always permanent and can change from time to time. MAC addresses are a unique identifier for a device that does not change. It can be understood as the serial number of the device.&#x20;

### More IPv4 Addressing

A devices IP address is built up of two parts. The beginning shows the network that the device is on. The rest of it is used to uniquely identify a device from other devices on a network.

### Network Troubleshooting

* Ping allows you to see if a host is running and is accepting connections.
* Ipconfig or ip a will show you if your device has a public and private ip address, and if your able to connect to the internet via ethernet or wireless card.
* Tracert allows you to see the route data takes on a network. It also allows you to see if there is latency when sending data.
* nslookup allows you to see the ip address of where a website or host is running if their domain name doesn't route you to the site.
