Type the command ipconfig.

102 | Lesson 5 2. Type the command ipconfig all. The results that appear should have much more information, including the MAC address as shown in Figure 5-4 the field is named “Physical Address”. The space after the word ipconfig is not necessary in this case; however, some commands will not function properly without a space. Figure 5-4 Ipconfig all command Notice that there is a section at the beginning of the results called “Windows IP Configuration.” This displays the name of the computer or “host name.” You can also find information by typing the command hostname. This section additionally shows a DNS suffix field, which is blank in this instance, but if the computer was a member of a domain, it would be populated similar to Figure 5-5. In the figure, the DNS suffix is dpro2.com, which is the domain name that this computer belongs to. If the com- puter does belong to a domain, an additional field called “DNS Suffix Search List” will be added. Figure 5-5 Ipconfig all command on a second host Implementing TCPIP in the Command Line | 103 The ipconfigall command also defines whether IP routing or WINS proxy is enabled. We will cover these services in Lesson 6. Up until now, these steps should be review. However, there are more options for the command ipconfig. You may hear professionals refer to “options” as “switches” or “parameters” as well. 3. Type the command ipconfig ?. This displays the help file for ipconfig, which is rather extensive. It describes what ipconfig is and what it does, and it shows the various options you can use with the command, as well as some examples. The results of this command are shown in Figure 5-6. Figure 5-6 Ipconfig ? command

4. Type the command ipconfig allcompartments.

Network adapters can be compartmentalized so that traffic from one doesn’t leak to the other e.g., VPN traffic on one adapter and private LAN traffic on another. This command shows the adapters in their compartmentalized format. You can also use the ipconfig allcompartments all command to see extended information about each compartment similar to ipconfig all.

5. Work with a dynamically assigned address:

a. On a computer that obtains its IP information automatically, type the command

ipconfig release. The ipconfig release command releases any IP configurations received from a DHCP server. Figure 5-7 shows an example of a released IP address. 104 | Lesson 5 There is actually no address assigned to the computer at this time. It is known as the IP 0.0.0.0.

b. Type the command ipconfig renew to retrieve an IP address and other IP

configurations. This should reconfigure the computer with the same IP address it used before. If the IP address has only been released for a short time, the renew option will reconfigure the address based on information stored in the registry. If no informa- tion is available or the address has expired after a certain amount of time, the computer will seek out a DHCP server on the network from which to obtain an IP address. These commands can be useful if a new DHCP server has been placed on the network or the current DHCP server has been reconfigured. The commands are also helpful if an error has occurred in the network adapter’s IP configuration, or if APIPA has gotten in the way and has self-assigned a 169.254.0.0 address to the client. The commands issued in step 5a and 5b pertain to IPv4; however, to release and renew IPv6 addresses, simply add a 6 to the option—for example ipconfig release6. More information about this process and DHCP is provided in Lesson 6. 6. Display, flush, and register DNS information:

a. Type the command ipconfig displaydns.

This displays Domain Name System records for the client computer, including localhost connections.

b. Type the command ipconfig flushdns.

This empties the DNS cache.

c. Type the command ipconfig registerdns.

This registers the computer with the nearest DNS server. The last two commands can be useful if there is an error with the DNS configuration on the client, or if a new DNS server or newly configured DNS server becomes live on the network. Figure 5-7 A released IP configuration