TCP AND DNS REFERENCE (macOS/Linux)

Network interfaces:
  ip -br address                  (Linux)
  ifconfig                        (macOS)

Route:
  ip route get 1.1.1.1            (Linux)
  route -n get 1.1.1.1            (macOS)

DNS:
  nslookup example.org

TCP port:
  nc -vz example.org 443

HTTPS HEAD:
  curl -I --max-time 10 https://example.org/

The commands above are read-only.