Computer Networks/Nslookup/Host

Nslookup is a command-line tool used to query a Domain Name System (DNS) server to obtain an IP address mapping or other DNS records. These activities will show you how to use the nslookup command to display host addresses.

Preparation

To prepare for this activity:

1. Start your operating system.
2. Log in if necessary.

Activity 1 - Observe DNS Settings

To observe DNS settings:

1. Open a command prompt.
2. Use ipconfig /all to display DNS settings.
3. Observe the DNS Servers address values.

Activity 2 - Display Host Addresses

To display host addresses:

1. Type nslookup www.google.com and press Enter.
2. Observe the server information. Notice the DNS server address matches one of the values listed for DNS Servers above.
3. Observe the results. Notice that both IPv4 and IPv6 addresses are displayed. Google has assigned both IPv4 and IPv6 addresses to this host.
4. Type nslookup ipv4.google.com and press Enter.
5. Observe the results. Notice that only IPv4 addresses are displayed. Google has not assigned an IPv6 address to this host name.
6. Type nslookup ipv6.google.com and press Enter.
7. Observe the results. Notice that only IPv6 addresses are displayed. Google has not assigned an IPv4 address to this host name.

Activity 3 - Use a Custom DNS Server

To use a custom DNS server:

1. Type nslookup www.google.com 8.8.8.8 and press Enter.
2. Observe the server information. Notice the DNS server address is 8.8.8.8.
3. Type nslookup www.google.com 8.8.4.4 and press Enter.
4. Observe the server information. Notice the DNS server address is 8.8.4.4.
5. Close the command prompt to complete this activity.

Readings

• Wikipedia: nslookup

References

• Microsoft TechNet: Nslookup