The following are tips for troubleshooting network issues:
Check network status: The first step you may want to perform when troubleshooting network issues is to check the Network Status pane of the Network pane of System Preferences. Network Status indicates whether port configurations are active and provides a brief description of their status.
Check network settings: In many cases, networking issues can be fixed by modifying the network settings in the Network pane of System Preferences.
Use Console: You can use Console to view log entries in the lookupd.log and ipfw.log files.
Use ifconfig: You can use ifconfig to get a bird's-eye view of your network settings, which is crucial when troubleshooting network issues.
Use ipconfig: If you want to find a rogue DHCP server in your local subnet, you can use the getpacket option of ipconfig to get the last DHCP or BOOTP offer packet received on a given interface. The packet includes the address of the DHCP server that is providing your computer with its IP address.
