updated notes

src/rhcsa.md

@@ -887,3 +887,29 @@ sudo vmstat 1 5 # Display the VM statistics every 1 second for 5 seconds
 ### top
 sudo top # Display the top processes then press m to sort by memory
 ```
+
+### Troubleshooting Network Issues
+```bash
+### nmtui
+sudo nmtui # Network Manager Text User Interface
+
+### nmcli
+sudo nmcli connection show # Display the network connections
+
+### ip route
+ip route show # Display the routes
+
+### ip addr
+ip -c addr # Display the network interfaces
+```
+
+### Troubleshooting DNS Issues
+```bash
+### check dns resolution with dig
+dig google.com # Query the DNS server for google.com
+
+### check dns resolution with resolv.conf
+sudo vim /etc/resolv.conf # Edit the resolv.conf file
+### change the nameserver to 8.8.8.8
+nameserver 8.8.8.8
+```