What function do the "networks" and "protocol" files provide?

Question

In a Windows system (in this case Windows 7) we have the "hosts" file in Windows\System32\drivers\etc

This location also has 3 other files:

1. networks
2. protocol
3. services

Note: the "services" file was explained in this other question. But what function does the "networks" and "protocol" files provide?

Answer 1

They are used to support functions in the networking libraries:

• protocol is used by getprotobyname

• network is used by applications doing loopback connections.

Further reading

• Issue 2215: windows net: replacement for /etc/protocols
• networks file
• networks(5)
• practical usage of /etc/networks file
• Protocol Numbers in Windows NT TCP/IP Network Administration
• What would be the “lo” interface equivalent on windows