How to troubleshoot network connectivity issues after configuring IP in Ubuntu?

If the network is not working after configuring the IP on Ubuntu, you can try the following troubleshooting methods:

1. Check IP configuration: Make sure you have correctly set up the IP address, subnet mask, and default gateway. You can use the commands ifconfig or ip addr to view the current network configuration.
2. Check the network interface: Make sure the IP address you have configured matches the network interface. You can use the command ifconfig or ip addr to view the current network interfaces and their status.
3. Check network devices and cables: Make sure network devices (like network cards) and network cables are not damaged. You can try unplugging and re-plugging the cables or replacing them.
4. Check the default gateway: Make sure the default gateway is configured correctly. You can use the command “route -n” or “ip route” to view the current default gateway.
5. Check DNS configuration: Make sure you have correctly configured the DNS server address. You can edit the /etc/resolv.conf file to configure the DNS server.
6. Check the firewall settings: If you have enabled a firewall (like iptables), make sure it allows relevant network traffic to pass through. You can use the command sudo iptables -L to view the current firewall rules.
7. Restarting the network service: You can try restarting the network service to apply the configuration. You can use the command sudo service networking restart or sudo systemctl restart networking to restart the network service.

If none of the above methods have resolved the issue, you can try using the ping command to test the network connection and see if you can communicate with other hosts. If the problem still persists, further troubleshooting of network devices may be necessary or contacting the network administrator.