Which of the following is NOT a type of token?

In the context of security and authentication methods, a token is a device or software that provides a means of verifying identity.

Hardware tokens are physical devices that often generate a code or contain a secure cryptographic key. Software tokens, on the other hand, are applications that can perform similar functions on computing devices. Biometric tokens utilize unique biological characteristics, such as fingerprints or iris scans, for authentication.

Network tokens are not recognized as a standard type of authentication token. While network security and protocols may involve various forms of authentication, the term "network token" lacks specific definition or standardized use in the same way that hardware, software, and biometric tokens are classified. Thus, the correct answer reflects the fact that "network token" does not fit within established categories of tokens used for secure access and verification processes.