Final answer:
The best method to secure a small network lacking an authentication server is using a Virtual Private Network (VPN).
Step-by-step explanation:
The best method to secure a small network lacking an authentication server would be to use a Virtual Private Network (VPN).
A VPN creates a secure, encrypted connection over a public network such as the internet, allowing users to securely access and transmit data between devices. It provides confidentiality and privacy by encrypting data, protecting it from unauthorized access.
A VPN would be an effective solution for securing a small network because it ensures that all communications between devices are encrypted and authenticated, even on an untrusted network.