Understanding Internet Protocol | 75
CONFIGURE CLASS C PRIVATE ADDRESSES
GET READY. In this exercise you will configure two computers with Class C private IP addresses, then verify the configuration through the use of ipconfig and ping:
1. Access the Local Area Connection Properties dialog box.
2. Click Internet Protocol Version 4, then click the Properties button. This displays the Internet Protocol Version 4 Properties dialog box. Write down the current settings so that you can return the computer to these settings at the end of the exercise.
3. Click the Use the following IP address radio button. This enables the other fields so you can type in the IP information. Enter the following:
• For the IP address of the fi rst computer, enter 192.168.50.1.
• For the IP address of the second computer, enter 192.168.50.2.
• For the Subnet mask of both computers, enter 255.255.255.0.
• Leave the Default gateway and the Preferred DNS server fi elds blank.
• When you are fi nished, the fi rst computer’s confi guration should look like Figure 4-4.
• If you have other computers, try confi guring their IP addresses as well; the host portion of the IP should ascend once for each computer: .3, .4, .5, and so on.
4. Click OK. Then, in the Local Area Connection Properties dialog box, click OK. This will complete and bind the configuration to the network adapter.
5. Test your configuration. We will do this in two ways, first with the ipconfig com- mand, and second with the ping command.
a. Open the command prompt. Type ipconfi g. Verify that the IP confi guration is accurate and corresponds to what you typed in the IP Properties window. If not, go back and check your Internet Protocol Properties dialog box.
b. Ping the other computer. Also try to ping any other computers that were confi g- ured as part of this Class C network (for example, ping 192.168.50.2). Make sure you get replies. If you do not, check the IP confi gurations of both computers.
Also make sure both computers are physically connected to the same network.
76 | Lesson 4
Up until now, we have only configured the IP address and Subnet mask fields of our IP Properties dialog box. To have a fully functional computer, however, we also need to config- ure two more fields.
The first such field is the default gateway field. The default gateway is the first IP address of the device that a client computer will look for when attempting to gain access outside the local network. This device could be a router, server, or other similar device; it is the device that grants access to the Internet or other networks. This device’s address is on the same network number as the client. So, for example, if the client is 192.168.50.1, the gateway might be 192.168.50.100. Many gateway devices come preconfigured with their own LAN IP, but this is almost always configurable. For example, the D-Link DIR-655 we accessed in the previous lesson was configured as 192.168.0.1, but we could change that if we wanted to. Without a default gateway address configured within our local computer’s IP Properties dialog box, we cannot gain access to any other networks. It is possible to have more than one gateway address in case the default gateway device fails. This can be done in Windows 7 by navigating to the Network Connections window, right clicking the network adapter in ques- tion (for example, Local Area Connection), selecting Properties, selecting Internet Protocol Version 4, and selecting the Properties button. In the Internet Protocol Version 4 Properties dialog box, click the Advanced button. Additional gateway addresses can be added to the Default gateways field.
The second field we need to configure is the DNS server address. The DNS server address is the IP address of the device or server that resolves DNS addresses to IP addresses. This could be a Windows Server or an all-in-one multifunction network device—it depends on the net- work environment. Also, it could be on the LAN (common in large networks) or located on the Internet (common in smaller networks). One example of a name resolution would be the domain name www.google.com, which currently resolves to the IP address 66.249.91.104.
To demonstrate this, try typing this command in the command prompt: ping www.google.
com. You should get results similar to “Reply from 66.249.91.104…”. Google can change its IP address at any time, but the results should be similar. By the way, this is an example of a public IP address. The whole concept here is that computers ultimately communicate by IP address. However, it is easier for people to remember www.google.com than it is for them to remember an IP address. The DNS server resolves domain names like www.proseware.com, host names like server1.proseware.com, and so on. Without this DNS server address, a client computer will not be able to connect by name to any resource on the Internet. DNS servers are also necessary in Microsoft domain environments. If your computer is a member of such an environment and the DNS server address is not configured properly, domain resources will most likely be inaccessible.
CONFIGURE CLASS C ADDRESSES, SUBNET MASKS, GATEWAY ADDRESS, AND DNS SERVER ADDRESS
GET READY. In this exercise, you will configure two computers with Class C private IP addresses, subnet masks, default gateways, and DNS server addresses. Then you will verify the configuration through the use of ipconfig and ping. Additional documentation will be required for steps 7 through 9:
1. Access the Local Area Connection Properties dialog box.
2. Click Internet Protocol Version 4, then click the Properties button. This displays the Internet Protocol Version 4 Properties dialog box. Write down the current settings so that you can return the computer to these settings at the end of the exercise.
3. Click the Use the following IP address radio button. This enables the other fields so you can type in the IP information. Enter the following:
• For the IP address of the fi rst computer, enter 192.168.50.1.
• For the IP address of the second computer, enter 192.168.50.2.
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Understanding Internet Protocol | 77
• For the Subnet mask of both computers, enter 255.255.255.0.
• For the Gateway address of both computers, enter 192.168.50.100.
• Then, in the next fi eld, enter a Preferred DNS server address of 192.168.50.201. Do this for both computers as well.
• When you are fi nished, the fi rst computer’s confi guration should look like Figure 4-5.
• If you have other computers, try confi guring their IP addresses as well; the host portion of the IP should ascend once for each computer: .3, .4, .5, and so on.
Figure 4-5
IPv4 Properties dialog box using a Class C private IP address, subnet mask, default gateway, and DNS server address
4. Click OK. Then, in the Local Area Connection Properties dialog box, click OK. This will complete and bind the configuration to the network adapter.
5. Now test your configuration. We will do this in two ways, first with the ipconfig com- mand, and second with the ping command.
a. Type ipconfi g. Verify that the IP confi guration is accurate and corresponds to what you typed in the IP Properties window. If not, go back and check your Internet Protocol Properties dialog box.
b. Ping the other computer. Also try to ping any other computers that were con- fi gured as part of this Class C network (for example, ping 192.168.50.2). Make sure you get replies. If you do not, check the IP confi gurations of both computers.
Also make sure the computers are physically connected to the same network.
6. Now attempt to connect to the Internet. You should not be able to! This is the case because we used fictitious gateway and DNS server addresses. (I can’t possibly know exactly what addresses you use on your network!) So . . . move on to step 7.
7. Get the following from your instructor or from other documentation:
• At least two static IP addresses that you can use for your client computers that will be allowed access to the gateway.
• The proper subnet mask, default gateway, and DNS server address that corre- spond with the static IPs.
8. Configure the computers with the new information and save the config.
9. Test the LAN connection with ping, and test the Internet connections by using a web browser to connect to a Web site. If either fails, check each address individually for any typos, IP conflicts, or other configuration mistakes.
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78 | Lesson 4
CERTIFICATION READY How can you define NAT and subnetting?
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