Automatic Proxy Configuration: It is now easier to specify complicated proxy configurations for an entire site. You can tell the Navigator to use different proxies depending on the URL or host being contacted. It's easier to specify a large number of hosts that should not be using a proxy.

The client then requests the CURL via HTTP. When making the request

it MUST transmit HTTP "Accept" headers indicating what CFILE formats

it is capable of accepting. For example, Netscape Navigator browsers

with versions 2.0 and beyond might include the following line in the

HTTP Request:

Accept: application/x-ns-proxy-autoconfig

The client MUST follow HTTP redirect directives (response codes 3xx)

returned by the server. The client SHOULD send a valid "User-Agent"

header.

A problem arises if the server requests credentials using HTTP BASIC or HTTP DIGEST authentication, as these authentication methods require that the user respond to a credential prompt dialog box. (In contrast, NTLM and Negotiate authenticate silently).

Many applications cannot handle showing prompts as a part of this workflow and will fail silently. To promote interoperability, IE11 also blocks the use of Proxy Configuration scripts that require authentication.

また、ネットワークでは、プロキシ自動設定(PAC)のクリアテキストHTTP URLスキームのサポートが非推奨になり、PACにはHTTPS URLスキームのみを使用する必要がある。