1100-Ch06.docx

Virtually all computers and mobile devices today are connected to some type of network and to the Internet. This means that configuring and troubleshooting computer networks is now a critical skill for IT professionals. This chapter focuses on applied networking with in-depth discussion on the forma...

Virtually all computers and mobile devices today are connected to some type of network and to the Internet. This means that configuring and troubleshooting computer networks is now a critical skill for IT professionals. This chapter focuses on applied networking with in-depth discussion on the format and architecture of media access control (MAC) addresses and Internet protocol (IP) addresses, both IPv4 and IPv6, that are used to connect computers to a network. Examples of how to configure static and dynamic addressing on computers are included. Also covered in this chapter is the configuration of both wired and wireless networks, firewalls, and IoT devices. You will learn how to configure network interface cards (NICs), connect devices to a wireless router, and configure a wireless router for network connectivity. You will learn how to configure wireless network basic wireless settings, Network Address Translation (NAT), firewall settings, and Quality of Service (QoS). You will also learn about firewalls, Internet of Things (IoT) devices, and network troubleshooting. At the end of the chapter you will learn the six step troubleshooting process and common problems and solutions for computer networks. Your networking skills should include the ability to configure wireless networks so that hosts can communicate, configure firewalls to filter traffic, verify network connectivity, and solve network connectivity problems. There are three labs included in this chapter where you will build these skills. In these labs you will configure basic settings on a wireless router and connect a PC to the wireless network, configure firewall settings to implement MAC address filtering, a DMZ, and single port forwarding, and finally, diagnose and solve network problems. Your fingerprint and mailing address are two ways to identify you and locate you. Your fingerprint usually does not change. Your fingerprint can be used to uniquely identify you, wherever your location. Your mailing address is different. It is your location. Unlike your fingerprint, your mailing address can change. Devices that are attached to a network have two addresses that are similar to your fingerprint and mailing address, as shown in the figure. These two types of addresses are the Media Access Control (MAC) address and the Internet Protocol (IP) address. The MAC address is hard-coded onto the Ethernet or wireless network interface card (NIC) by the manufacturer. The address stays with the device regardless of what network the device is connected to. A MAC address is 48 bits and can be represented in one of the three hexadecimal formats shown in the table below. P addressing is assigned by network administrators based on the location within the network. When a device moves from one network to another, its IP address will most likely change. An IP version 4 (IPv4) address is 32 bits and represented in dotted decimal notation. An IP version 6 (IPv6) address is 128 bits and is represented in hexadecimal format, Today, your computer probably has an IPv4 and an IPv6 address, as shown for the laptop in the figure. In the early 1990s, there was a concern about running out of IPv4 network addresses. The Internet Engineering Task Force (IETF) began to look for a replacement. This led to the development of IPv6. Currently, IPv6 is operating alongside IPv4 and is beginning to replace it. The Figure shows output for the command **ipconfig /all** on the laptop. The output is highlighted to show the MAC address and two IP addresses. **Note**: Windows OS calls the NIC an Ethernet adapter and the MAC address a physical address. When you manually configure a device with an IPv4 address, you enter it in dotted decimal format, as shown for a Windows computer in the figure. Each number separated by a period is called an octet because it represents 8 bits. Therefore, the 32-bit address 192.168.200.8 has four octets. An IPv4 address is composed of two parts. The first part identifies the network. The second part identifies this device on the network. The subnet mask is used by the device to determine the network. For example, the computer in the figure uses the subnet mask 255.255.255.0 to determine that the IPv4 address 192.168.200.8 belongs to the 192.168.200.0 network. The.8 portion is this device's unique host portion on the 192.168.200 network. Any other device with that same 192.168.200 prefix will be on the same network but have a different value for the host portion. Devices with a different prefix will be on a different network. To see this at the binary level, you can convert the 32-bit IPv4 address and subnet mask to their binary equivalents, as shown in figure below. A one bit in the subnet mask means that bit is part of the network portion. So, the first 24 bits of the 192.168.200.8 address are network bits. The last 8 bits are host bits. When your device prepares data to send out on the network, it must first determine whether to send data directly to the intended receiver or to a router. It will send it directly to the receiver if the receiver is on the same network. Otherwise, it will send the data to a router. A router then uses the network portion of the IP address to route traffic between different networks. For example, if the Windows computer in figure above has data to send to a host at 192.168.200.25, it sends the data directly to that host because it has the same prefix of 192.168.200. If the destination's IPv4 address is 192.168.201.25, then the Window's computer will send the data to a router. IPv6 overcomes the address space limitations of IPv4. The 32-bit IPv4 address space provides approximately 4,294,967,296 unique addresses. The 128-bit IPv6 address space provides 340,282,366,920,938,463,463,374,607,431,768,211,456 addresses, or 340 undecillion addresses. The 128 bits of an IPv6 addresses are written as a string of hexadecimal values, with letters expressed in lowercase. Every 4 bits is represented by a single hexadecimal digit for a total of 32 hexadecimal values. The examples shown below are fully expanded IPv6 addresses. Two rules help reduce the number of digits needed to represent an IPv6 address. The first rule to help reduce the notation of IPv6 addresses is to omit any leading 0s (zeros) in any 16-bit section. For example, in the example above: - **0db8** can be represented as **db8**, in the first IPv6 address - **0123** can be represented as **123**, in the second IPv6 address - **0001** can be represented as **1**, in the third IPv6 address **Note**: IPv6 addresses must be represented in lowercase letters, but you may often see them as uppercase. **Rule 2 -- Omit All 0 Segments** The second rule to help reduce the notation of IPv6 addresses is that a double colon (::) can replace any group of consecutive zeros. The double colon (::) can only be used once within an address, otherwise there would be more than one possible resulting address. In a small network, you can manually configure each device with proper IP addressing. You would assign a unique IP address to each host within the same network. This is known as static IP addressing. On a Windows computer, as shown in the figure on the left, you can assign the following IPv4 address configuration information to a host: - **IP address** - identifies this device on the network - **Subnet mask** - is used to identify the network on which this device is connected - **Default gateway** - identifies the router that this device uses to access the internet or another network - **Optional values** - such as the preferred Domain Name System (DNS) server address and the alternate DNS server address Rather than manually configure every device, you can take advantage of implementing a Dynamic Host Configuration Protocol (DHCP) server. A DHCP server automatically assigns IP addresses, which simplifies the addressing process. Automatically configuring some of the IP addressing parameters also reduces the possibility of assigning duplicate or invalid IP addresses. By default, most host devices are configured to request IP addressing from a DHCP server. The default setting for a Windows computer is shown in the figure. When a computer is set to obtain an IP address automatically, all other IP addressing configuration boxes are not available. This process is the same for a wired or wireless NIC. A DHCP server can automatically assign the following IPv4 address configuration information to a host: - IPv4 address - Subnet mask - Default gateway - Optional values, such as a DNS server address DHCP is also available for automatically assigning IPv6 addressing information. **Note**: The steps to configure a Windows computer is beyond the scope of this topic. Dynamic Host Configuration Protocol (DHCP) works in a client/server mode, where DHCP clients request available IP configurations from a DHCP server. A DHCP server is configured with a scope (i.e., a pool or a range) of addresses that it can lease to requesting DHCP clients. **Note**: The DHCP server can be a dedicated server or a router configured to provide DHCP services.The DHCP scope should not include manually assigned or reserved IP addresses such as the default gateway address, switch management address, printer address, and more. As shown in the figure, when the DHCP client boots (or otherwise wants to join a network), it initiates the following four-step process to obtain a lease. 1. The DHCP client broadcasts a DHCPDISCOVER message to request an IP configuration from a DHCP server. 2. The DHCP server chooses an available IP configuration from its configured scope, and sends a DHCPOFFER unicast message to the client MAC address. The IP configuration can contain the IP address, subnet mask, default gateway, DNS servers, and the period of time (i.e., the lease) that the host can use the IP configuration. 3. The client then officially requests the IP configuration by sending a broadcast DHCPREQUEST message to the DHCP Server. 4. The server removes the IP configuration from its pool of available IP configurations and sends a unicast acknowledgement (DHCPACK) to the DHCP client to confirm that it can use the address until the lease expires. **Note**: DHCP messages are sent using UDP ports 67 (server) and UDP port 68 (clients). DHCP servers listen for client messages on UDP port 67 and DHCP clients listen for messages from servers on UDP port 68. Once a client receives the DHCPACK from the server, it send out an ARP message to the provided IP address to make sure it is not already assigned on the network. ARP (address resolution protocol) is a network protocol to discover the MAC address of a device using an IP address. If there is no response to the ARP request, then the host can use the IP configuration. If the host receives an ARP reply, then it restarts the DHCP process to obtain a different IP configuration. **DHCP Lease**\ The client must contact the DHCP server periodically to extend the lease. This lease mechanism ensures that moved or power-off clients do not keep addresses that they no longer need. When a lease expires, the DHCP server returns the address to the pool where it can be reallocated as necessary. **DHCP Reservations**\ It is also possible to ensure that some hosts, such as servers and printers, are always assigned the same IP address when they connect. To do so, a DHCP server is configured with a reserved list of IP addresses based on the requesting DHCP client's MAC address. Therefore, when a host sends a DHCPDISCOVER message, the DHCP server looks in its DHCP reserved address list for a matching MAC address. If it finds a match, then it sends a DHCPOFFER with the reserved IP address. Virtual LANs (VLANs) provide segmentation and organizational flexibility in a switched network. A group of devices within a VLAN communicate as if each device was attached to the same switch. VLANs are based on logical connections, instead of physical connections. An administrator can segment VLANs based on factors such as function, team, or application, without regard for the physical location of the users or devices. In the figure for example, a faculty member computer (PC1) is connected to S2 on VLAN 10. PC1 could communicate with another faculty member using PC4 connected to S3. Notice how both hosts are configured on network address 192.168.10.0/24. By default, all switch ports are assigned to VLAN 1. However, you can assign the PCs to different VLANs by configuring their interconnecting port. For example, figure below displays a sample configuration of switch S2. Notice that we first create the VLANs and assign them names. This makes it easier to work with the VLANs. Next, we configure the ports connecting to the PCs to the corresponding VLANs. Once the VLAN information is configured on the other switches, the faculty member using PC1 would be able to communicate with PC4 because they are on the same VLANs. If the faculty member wanted to send something to PC5 which is assigned to VLAN 30, then the services of a router would be required. VLANs help reduce excessive broadcast traffic and implement access and security policies between groups of users. Link-local addresses for IPv4 and IPv6 are used by a device to communicate with other computers connected to the same network within the same IP address range. The major difference between IPv4 and IPv6 is the following: - An IPv4 device uses the link-local address if the device cannot obtain an IPv4 address. - An IPv6 device must always be dynamically or manually configured with a link-local IPv6 address. **IPv4 Link-Local Address** If your Windows computer cannot communicate with a DHCP server to obtain an IPv4 address, then Windows automatically assigns an Automatic Private IP Addressing (APIPA) address. This link-local address is in the range of 169.254.0.0 to 169.254.255.255. **IPv6 Link-Local Address** Like IPv4, the IPv6 link-local address enables your device to communicate with other IPv6-enabled devices on the same network and only on that network. Unlike IPv4, every IPv6 enabled device is required to have a link-local address. IPv6 link-local addresses are in the range of fe80:: to febf::. For example, in the figure, the links to other networks are down (not connected) as notate by the red Xs. However, all the devices on the LAN can still use link-local IPv6 addresses to communicate with each other. **Note**: Unlike IPv4 link-local addresses, IPv6 link-local addresses are used in a variety of processes including network discovery protocols and routing protocols. This is beyond the scope of this course. As a computer technician, you must be able to support the networking needs of your customers. Therefore, you must be familiar with: - **Network components** -- Includes wired and wireless network interface cards (NIC) and network devices such as switches, wireless access points (APs), routers, multipurpose devices, and more. - **Network design** -- Involves knowing how networks are interconnected to support the needs of a business. For instance, the needs of a small business will differ greatly from the needs of a large business. Consider a small business with 10 employees. The business has contracted you to connect their users. As shown in the figure, a home or small office wireless router could be used for such a small number of users. These routers are multiple purpose and typically provide router, switch, firewall, and access point capabilities. In addition, these wireless routers often provide a variety of other services including DHCP. If the business was much larger, then you would not use a wireless router. Instead, you would consult with a network architect to design a network of dedicated switches, access points (AP), firewall appliances, and routers. Regardless of network design, you must know how to install network cards, connect wired and wireless devices, and configure basic network equipment. **Note**: This chapter will focus on connecting and configuring a small office or home wireless router. The configurations will be demonstrated using Packet Tracer. However, the same functionality and similar graphical user interface (GUI) elements exist in all wireless routers. You can purchase a variety of low-cost wireless routers online and from consumer electronic stores. Search the internet for "wireless router reviews" to research current recommendations. A NIC is required to connect to the network. As shown in the figures, there are different types of NICs. Ethernet NICs are used to connect to Ethernet networks and wireless NICs are used to connect to 802.11 wireless networks. Most NICs in desktop computers are integrated into the motherboard or connected to an expansion slot. NICs are also available in a USB form factor. Many computers purchased today come with a wired and wireless network interface integrated on the motherboard. Follow the steps to install adapter cards if you are installing a NIC inside the computer. A wireless NIC for a desktop device has an external antenna connected to the back of the card or attached with a cable so that it can be positioned for the best signal reception. You must connect and position the antenna. Sometimes a manufacturer publishes new driver software for a NIC. A new driver might enhance the functionality of the NIC, or it might be needed for operating system compatibility. The latest drivers for all supported operating systems are available for download from the manufacturer's website. When installing a new driver, disable virus protection software to ensure that the driver installs correctly. Some virus scanners detect a driver update as a possible virus attack. Install only one driver at a time; otherwise, some updating processes might conflict. A best practice is to close all applications that are running so that they are not using any files associated with the driver update. **Note**: An example of Windows Device Manager and the place to update a NIC's driver is shown in the figure. However, details of how to update drivers for specific devices and operating systems is beyond the scope of this topic. fter the NIC driver is installed, the IP address settings must be configured. For Windows computers, IP addressing is dynamic by default. After you physically connect a Windows computer to the network, it will automatically send out a request for IPv4 addressing the DHCP server. If a DHCP server is available, the computer will receive a message will all its IPv4 addressing information. **Note**: Dynamic addressing for IPv6 can also use DHCP but is beyond the scope of this course. This dynamic, default behavior is also typically for smartphones, tablets, gaming consoles, and other end-user devices. Static configuration is normally the job of a network administrator. However, you should be familiar with how to access the IP addressing configuration for any device you are asked to manage. To find IP addressing configuration information, search the internet for "IP address configuration for device" where "device" is replaced with your device, such as "iPhone". For example, the figure shows the dialog box for viewing and changing a Windows computer's IPv6 configuration. Internet Control Message Protocol (ICMP) is used by devices on a network to send control and error messages. There are several different uses for ICMP, such as announcing network errors, announcing network congestion, and troubleshooting. Ping is commonly used to test connections between computers. To see a list of options that you can use with the ping command, type **ping /? **in the Command Prompt window,  Ping works by sending an ICMP echo request to the IP address you entered. If the IP address is accessible, the receiving device then sends back an ICMP echo reply message to confirm connectivity. You can also use the **ping** command to test connectivity to a website by entering the website's domain name. For example, if you enter **ping cisco.com** your computer will first use DNS to find the IP address and then send the ICMP echo request to that IP address, he steps to connect a wired device to the internet in a home or small office are as follows: **Step 1: Connect a network cable to the device.** **Step 2: Connect the device to a switch port.** Connect the other end of the cable to an Ethernet port on the wireless router, such as one of the four yellow switch ports shown in the figure below. In a SOHO network, the laptop would most likely connect to a wall jack which in turn connects to a network switch. **Step 3: Connect a network cable to the wireless router internet port.** On the wireless router, connect an Ethernet cable to the port labeled Internet (blue port in the figure below). This port might also be labeled WAN. **Step 4: Connect the wireless router to the modem.** The blue port in the figure is an Ethernet port that is used to connect the router to a service provider device, such as a DSL or cable modem. **Step 5: Connect to the service provider's network.** The modem is then connected to the service provider's network, as shown in the figure below. **Note**: A separate modem isn't necessary if the wireless router is a router/modem combination. **Step 6: Power all devices and verify physical connections.** Turn on the broadband modem and plug in the power cord to the router. After the modem establishes a connection to the ISP, it will begin communicating with the router. The laptop, router, and modem LEDs will light up, indicating communication. The modem enables the router to receive the network information necessary to gain access to the internet from the ISP. This information includes public IPv4 addresses, subnet mask, and DNS server addresses. With the depletion of public IPv4 addresses, many ISPs are also providing IPv6 addressing information as well. **Note**: Cable or DSL modem configuration is usually done by the service provider's representative either on-site or remotely through a walkthrough with you on the phone. If you buy the modem, it will come with documentation for how to connect it to your service provider which will most likely include contacting your service provider for more information. Most home and small office wireless routers are ready for service out of the box. They preconfigured to be connected to the network and provide services. For example, the wireless router uses DHCP to automatically provide addressing information to connected devices. However, wireless router default IP addresses, usernames, and passwords can easily be found on the internet. Just enter the search phrase "default wireless router IP address" or "default wireless router passwords" to see a listing of many websites that provide this information. Therefore, your first priority should be to change these defaults for security reasons. To gain access to the wireless router's configuration GUI, open a web browser. In the address field, enter the default IP address for your wireless router. The default IP address can be found in the documentation that came with the wireless router or you can search the internet. The figure shows the IPv4 address 192.168.0.1, which is a common default for many manufacturers. A security window prompts for authorization to access the router GUI. The word admin is commonly used as the default username and password. Again, check your wireless router's documentation or search the internet. In a small office or home network, one wireless router may suffice to provide wireless access to all the clients. However, if you want to extend the range beyond approximately 45 meters indoors and 90 meters outdoors, you can add wireless access points. As shown in the wireless mesh network in the figure, two access points are configured with the same WLAN settings from our previous example. Notice that the channels selected are 1 and 11 so that the access points do not interfere with channel 6 configured previously on the wireless router. Extending a WLAN in a small office or home has become increasingly easier. Manufacturers have made creating a wireless mesh network (WMN) simple through smartphone apps. You buy the system, disperse the access points, plug them in, download the app, and configure your WMN in a few steps. Search the internet for "best wi-fi mesh network system" to find reviews of current offerings. On a wireless router, if you look for a page like the Status page shown in the figure, you will find the IPv4 addressing information that the router uses to send data to the internet. Notice that the IPv4 address is 209.165.201.11 is a different network than the 10.10.10.1 address assigned to the router's LAN interface. All the devices on the router's LAN will get assigned addresses with the 10.10.10 prefix. The 209.165.201.11 IPv4 address is publicly routable on the internet. Any address with the 10 in the first octet is a private IPv4 address and cannot be routed on the internet. Therefore, the router will use a process called Network Address Translation (NAT) to convert private IPv4 addresses to Internet-routable IPv4 addresses. With NAT, a private (local) source IPv4 address is translated to a public (global) address. The process is reversed for incoming packets. The router is able to translate many internal IPv4 addresses into public addresses, by using NAT. Some ISPs use private addressing to connect to customer devices. However, eventually, your traffic will leave the provider's network and be routed on the internet. To see the IP addresses for your devices, search the internet for "what is my IP address." Do this for other devices on the same network and you will see that they all share the same public IPv4 address. NAT makes this possible by tracking the source port numbers for every session established by a device. If your ISP has IPv6 enabled, you will see a unique IPv6 address for each device. Many home and small office routers have an option for configuring Quality of Service (QoS). By configuring QoS, you can guarantee that certain traffic types, such as voice and video, are prioritized over traffic that is not as time-sensitive, such as email and web browsing. On some wireless routers, traffic can also be prioritized on specific ports. The figure is a simplified mockup of a QoS interface based on a Netgear GUI. You will usually find the QoS settings in the advanced menus. If you have a wireless router available, investigate the QoS settings. Sometimes, these might be listed under "bandwidth control" or something similar. Consult the wireless router's documentation or search the internet for "qos settings" for your router's make and model. Universal Plug and Play (UPnP) is a protocol that enables devices to dynamically add themselves to a network without the need for user intervention or configuration. Although convenient, UPnP is not secure. The UPnP protocol has no method for authenticating devices. Therefore, it considers every device trustworthy. In addition, the UPnP protocol has numerous security vulnerabilities. For example, malware can use the UPnP protocol to redirect traffic to different IP addresses outside your network, potentially sending sensitive information to a hacker. Many home and small office wireless routers have UPnP enabled by default. Therefore, check this configuration and disable it, as shown in the figure. Search the internet for "vulnerability profiling tools" to determine if your wireless router is exposed to UPnP vulnerabilities. A demilitarized zone (DMZ) is a network that provides services to an untrusted network. An email, web, or FTP server is often placed into the DMZ so that the traffic using the server does not come inside the local network. This protects the internal network from attacks by this traffic but does not protect the servers in the DMZ in any way. It is common for a firewall to manage traffic to and from the DMZ. For example, the Web Server in the figure below is in the DMZ and is statically assigned the IPv4 address 10.10.10.50. On a wireless router, you can create a DMZ for one device by forwarding all traffic ports from the internet to a specific IP address or MAC address. A server, game machine, or web camera can be in the DMZ so that the device can be accessed by anyone. The figure below shows a typical configuration where any traffic sources from the internet will be redirected to the Web Server's IPv4 address 10.10.10.50. However, the Web Server is exposed to attacks from hackers on the internet and should have firewall software installed. Hardware firewalls can be used to block TCP and UDP ports to prevent unauthorized access in and out of a LAN. However, there are situations when specific ports must be opened so that certain programs and applications can communicate with devices on different networks. Port forwarding is a rule-based method of directing traffic between devices on separate networks. When traffic reaches the router, the router determines if the traffic should be forwarded to a certain device based on the port number found with the traffic. Port numbers are associated with specific services, such as FTP, HTTP, HTTPS, and POP3. The rules determine which traffic is sent on to the LAN. For example, a router might be configured to forward port 80, which is associated with HTTP. When the router receives a packet with the destination port of 80, the router forwards the traffic to the server inside the network that serves web pages. In the figure, port forwarding is enabled for port 80 and is associated with the web server at IPv4 address 10.10.10.50. Port triggering allows the router to temporarily forward data through inbound ports to a specific device. You can use port triggering to forward data to a computer only when a designated port range is used to make an outbound request. For example, a video game might use ports 27000 to 27100 for connecting with other players. These are the trigger ports. A chat client might use port 56 for connecting the same players so that they can interact with each other. In this instance, if there is gaming traffic on an outbound port within the triggered port range, inbound chat traffic on port 56 is forwarded to the computer that is being used to play the video game and chat with friends. When the game is over and the triggered ports are no longer in use, port 56 is no longer allowed to send traffic of any type to this computer. MAC address filtering specifies exactly which device MAC addresses are allowed to or blocked from sending data on your network. Many wireless routers only give you the option of allowing or blocking MAC addresses, but not both. Technicians will typically configure allowed MAC addresses. The MAC address for your Windows computer can be found with the **ipconfig /all** command, as shown in the figure. You may need to search the internet for where to find the MAC address on a specific device. Finding the MAC address is not always straight forward because not all devices call it a MAC address. Windows calls it a "Physical Address", On an iPhone it is called the "Wi-Fi Address" and on an Android it is called "Wi-Fi MAC address", as shown below. additionally, your device may have two or more MAC addresses. For example, the PlayStation 4 in the figure has two MAC addresses: one for wired networks and one for wireless networks. Finally, consider the fact that new devices might be added to the network at any time. You can see how the technician responsible for manually configuring all these MAC addresses might be overwhelmed. Imagine having to manually enter and maintain dozens of MAC addresses in an interface such as the one shown below. However, MAC address filtering may be your only option. Better solutions, such as port security, require purchasing a more expensive router or a separate firewall device, and are beyond the scope of this course. Whitelisting and blacklisting specify which IP addresses are allowed or denied on your network. Similar to MAC address filtering, you can manually configure specific IP addresses to allow or deny into your network. On a wireless router, this is typically done using an access list or access policy, as shown in the figure. Refer to your wireless router's documentation for specific steps or search the internet for a tutorial. Whitelisting is a good tool for allowing your users, such as children or employees, access to those IP addresses you approve. You can also blacklist or explicitly block known sites. However, similar to MAC address filtering, this can become burdensome. Better solutions exist. Search the internet for "parental control software" and "content filters". The internet of today is significantly different than the internet of past decades. The internet of today is more than email, web pages, and file transfers between computers. The evolving internet is becoming an Internet of Things (IoT). No longer will the only devices accessing the internet be computers, tablets, and smartphones. The sensor-equipped, internet-ready devices of tomorrow will include everything from automobiles and biomedical devices, to household appliances and natural ecosystems. You may already have some IoT devices in your home. You can buy all kinds of connected devices including thermostats, light switches, security cameras, door locks, and voice-enabled digital assistants (such as Amazon Alexis and Google Home). These devices can all be connected to your network. In addition, many of them can be directly managed from a smartphone app, At this point in its infancy, the IoT market has not yet agreed upon a set of standards for IoT device installation and configuration. Configuring IoT devices is very much device specific. Consult the manufacturer's documentation or website for configuration guides. In this course, you will use Packet Tracer to explore a basic IoT device configuration. The figure shows all the IoT devices in Packet Tracer. Packet Tracer also includes a number of sensors and actuators. In the figure, the sensors are shown in the bottom panel of the Packet Tracer interface. 1. Identify the Problem: Gather information about the issue, including symptoms and any recent changes to the system. 2. Establish a Theory of Probable Cause: Based on the information gathered, hypothesize what might be causing the problem. 3. Test the Theory to Determine Cause: Verify the hypothesis by testing it. If the theory is not confirmed, establish a new theory and test again. 4. Establish a Plan of Action to Resolve the Problem and Implement the Solution: Once the cause is identified, develop and execute a plan to fix the issue. 5. Verify Full System Functionality and, if Applicable, Implement Preventive Measures: Ensure the solution has resolved the problem and that the system is fully operational. Implement measures to prevent recurrence. 6. Document Findings, Actions, and Outcomes: Record the problem, the steps taken to resolve it, and the final outcome for future reference. Open-ended questions are designed to encourage a full, meaningful answer using the respondent's own knowledge and feelings. Unlike closed-ended questions, which can be answered with a simple "yes" or "no," open-ended questions require more detailed responses. They are often used to gain deeper insights and foster discussion. Closed-ended questions are designed to elicit specific, concise responses, often limited to a single word or a choice from predefined options. These questions typically aim to gather quantitative data or confirm specific information. [Examples include questions that can be answered with "yes" or "no," or those that offer multiple-choice answers^1^](https://en.wikipedia.org/wiki/Closed-ended_question)[^2^](https://www.appinio.com/en/blog/market-research/close-ended-questions). For instance, instead of asking "How do you feel about the new policy?" (an open-ended question), a closed-ended version might be \"Do you agree with the new policy? [(Yes/No)\"](https://www.formpl.us/blog/close-ended-questions) In this chapter, you learned how to configure NICs, connect devices to a wireless router, and configure a wireless router for network connectivity. You also learned about firewalls, IoT devices, and network troubleshooting. You learned about the 48-bit MAC addresses that identified devices connected to an Ethernet LAN, and the two types of IP addresses, IPv4 and IPv6. IPv4 addresses are 32-bits in length and are written in dotted decimal format while IPv6 addresses are 128-bits in length and written in hexadecimal format. Configuring an IP address on a device can be done manually or dynamically by using DHCP. You learned that manual, or static addressing, is appropriate for small networks while DHCP is best suited for larger networks. In addition to an IP address, DHCP can also automatically assign the subnet mask, default-gateway, and address of DNS servers. You configured a NIC to use DHCP on a Windows computer through a lab exercise. You were able to verify network configuration using the ipconfig /all command in Windows and test connectivity by using ping. You then learned how to configure a wireless network including the configuration of a wireless router with basic wireless settings, NAT, firewall settings, and QoS. You then completed two labs one about configuring a wireless network and then a lab on configuring firewall settings. The wireless network lab had you configure basic wireless settings on a wireless host and an access point and then test connectivity. In the firewall lab you configured MAC filtering, a DMZ, and port forwarding. The internet today is becoming more than just computers, tablets, and smartphones. It is becoming an IoT. These things are sensor-equipped, internet-ready devices that include automobiles, biomedical devices, household appliances, and natural ecosystems. You used Packet Tracer to explore IoT devices and their basic configuration. At the end of the chapter, you learned the six steps in the troubleshooting process as they pertain to networks.