Which configuration option is suitable for explicit mode deployment?

Explicit forward mode deployment requires client applications, such as web browsers, to be explicitly configured to send web traffic to the proxy. A Proxy Auto-Config (PAC) file is a common and scalable method for this configuration. The PAC file contains JavaScript logic that instructs the browser which proxy to use for a given URL, or whether to connect directly. This client-side configuration is the defining characteristic of an explicit deployment.

B. WCCP: Web Cache Communication Protocol (WCCP) is a network-level protocol used to transparently redirect traffic to a proxy without any client-side configuration.
C. ITD: Intelligent Traffic Director (ITD) is a Cisco Nexus feature for transparently load-balancing and redirecting traffic to a group of appliances, which is a transparent deployment method.
D. PBR: Policy-Based Routing (PBR) is a technique used on routers and switches to transparently forward traffic to a specific next-hop (like a proxy) based on defined policies.

1. Cisco Web Security Appliance Best Practices Guide. (2018). Cisco Systems, Inc. In the "Deployment Modes" section, it states, "In explicit forward mode, you must configure user agent applications (such as web browsers) to send requests directly to the Web Security appliance... You can use a Proxy Auto-Configuration (PAC) file to direct user agents to the correct proxy." (Page 10).

2. AsyncOS 14.5 for Cisco Web Security Appliances User Guide. (2022). Cisco Systems, Inc. The section "Deployment Modes for the Web Proxy" describes Explicit Forward Mode: "You must configure client web browsers to send HTTP and HTTPS requests to the Web Security appliance." It later details using PAC files for this purpose under "Using PAC Files to Direct Web Traffic." (Chapter: The Web Proxy, Page 1-3).

3. Configuring Web Cache Services Using WCCP. (2023). Cisco Systems, Inc. This document describes WCCP as a technology for transparent redirection: "WCCP enables you to transparently redirect traffic that is destined for a specific device." (Introduction section).