Finding Your Public IP Address- Ciscco considers DNS in more detail.
Network Address Translation (NAT), described in Chapter 2, can sometimes make verifying the connection between a host and servers on the Internet difficult. Figure 4-19 illustrates.
Figure 4-19 Finding Your Public IP Address
In Figure 4-19, host A communicates with server D using its local interface address 192.0.2.100. Unknown to A, router B has NAT configured and is translating 192.0.2.100 to 203.0.113.45 (and some port number, but the port number is not essential for this example).
In this example, 192.0.2.100 is the private IP address, and 203.0.113.45 is the public IP address.
If there is a problem with the host A to server D communication, and the user would like to know what the network looks like from server D’s perspective, the user needs to know what IP address D is using to reach A—or rather, A’s public IP address.
The simplest way to discover A’s public IP address is to open a web browser and use a service. Several are available on the Internet, including
• If you type “what is my IP address” into Google search, the search engine will show the public IP address for your host on a web page.
• If you open the web page at https://checkip.amazonaws.com, it will display the public IP address of your host.
• If you open the web page at https://infoip.io, it will display information about the public IP address and location of your host.
Some hosts, particularly those running Linux, may not have a web browser installed. You can use many of these same sites to find your public IP from the command line, such as
<97.95.136.20>
$ curl -s https://checkip.amazonaws.com
97.95.136.20
Chapter Review
This chapter took a break from the theory of how networks work and focused on how to configure three different kinds of hosts—Windows 11, macOS, and Linux—to connect to a wired network. There are multiple ways to configure these hosts, including GUI and CLI options. Network engineers tend to prefer CLIs for configuring and managing devices.
This chapter also considered two of the most important tools for verifying connectivity: ping and traceroute. Part V of this book will return to verifying connectivity and troubleshooting networks.
At this point, we have covered the basic process of sending a packet through a network. You should now understand IP addressing, routers, switches, and basic host wired network configuration. In the next chapter, we will take a break from operational internals and look at an overview of the various kinds of devices making up a computer network.
One key to doing well on the exams is to perform repetitive spaced review sessions. Review this chapter’s material using either the tools in the book or interactive tools for the same material found on the book’s companion website. Refer to the online Appendix D, “Study Planner,” element for more details.
Table 4-2 outlines the key review elements and where you can find them. To better track your study progress, record when you completed these activities in the second column.
Table 4-2 Chapter Review Tracking Review All the Key Topics
Table 4-3 lists the key topics for this chapter.
Table 4-3 Key Topics for Chapter 4
Key Terms You Should Know
Key terms in this chapter include
Settings app Control Panel CLI Powershell ipconfig ifconfig ping traceroute public IP address
Concepts and Actions
Review the concepts considered in this chapter using Table 4-4.
You can cover the right side of this table and describe each concept or action in your own words to verify your understanding.
Table 4-4 Concepts and Actions
