The Cost of Expanding a Subnet into NO_PROXY

Enumerating every IP in a /16 turns a short bypass policy into tens of thousands of strings. Operating systems limit the arguments and environment passed to a process; an oversized value can prevent unrelated commands from starting. Shell expansion can hit practical limits too.

The list also concerns literal addresses. It does not establish that the client resolves a destination hostname and compares its answers with every entry. A request for catalog.office.example can still use the proxy.

Check the consuming client and version for a supported range rule. curl added CIDR matching in 7.86.0; another application's library may have different support. Use name rules when the policy concerns names.

Where the required selection is unsupported, consider a documented routing callback or managed proxy configuration. Numeric-suffix approximations and huge generated lists obscure the intended network boundaries instead of reliably expressing them.