Examine your system’s TCP/IP configuration using ifconfig eth0 or a similar command for your network interface. Are you using DHCP? What type of subnet are you running with? Is it a class A, B, or C address? Are you using a private address? Experiment with taking the interface offline using ifconfig eth0 down and ifconfig eth0 up.
Examine the contents of /etc/services. How many protocols do you recognize?
Use the dig command to locate information from DNS servers about a domain name.
Examine your /etc/hosts file. How much name resolution is accomplished in this file manually?
Examine your /etc/resolv.conf file. How many DNS servers do you have available?
Execute netstat -r. How many routes are reported? What are the routes to the local network and interface for?
Use traceroute to examine the route to a favorite website.