Merge branch 'docs-linux-networking-troubleshooting-commands' into 'master'

Expand Linux cheat sheet's Networking section

See merge request gitlab-org/gitlab!52973

doc/administration/troubleshooting/linux_cheat_sheet.md

@@ -304,6 +304,24 @@ whois <ip_address> | grep -i "orgname\|netname"
 
 # Curl headers with redirect
 curl --head --location "https://example.com"
+
+# Test if a host is reachable on the network. `ping6` works on IPv6 networks.
+ping example.com
+
+# Show the route taken to a host. `traceroute6` works on IPv6 networks.
+traceroute example.com
+mtr example.com
+
+# List details of network interfaces
+ip address
+
+# Check local DNS settings
+cat /etc/hosts
+cat /etc/resolv.conf
+systemd-resolve --status
+
+# Capture traffic to/from a host
+sudo tcpdump host www.example.com
 ```
 
 ## Package Management