There is no parameter called "All". It has to be set to "Any".

Answer B: The dropdown options for the Source field are: *Any *All zones *Local Zone *Named Source: https://www.cisco.com/c/dam/en/us/td/docs/voice_ip_comm/expressway/config_guide/X8-8/Cisco-Expressway-Basic-Configuration-Deployment-Guide-X8-8.pdf

Tough question. If the exam says "All Zones", then that's the answer. • To reduce toll fraud risks, avoid using the "Any" wildcard for the Source setting. For extra security, you can set the rule's Source option to All zones. This means the query is only sent to the target zone if it came from any configured zone or the Local Zone. https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/expressway/admin_guide/X14-0/exwy_b_cisco-expressway-administrator-guide/exwy_m_dial-plan-and-call-processing.html

From the expressway help file below. The difference between the two is that any also blocks unregistered devices. I would go with ANY as the answer The sources of the requests for which this rule applies. Any: locally registered devices, neighbor or traversal zones, and any non-registered devices. All zones: locally registered devices plus neighbor or traversal zones.

or maybe the answer refers to any of the all 3 options above O_o ?

No, because the possible choices at Expressway are: Any: locally registered devices, neighbor or traversal zones, and any non-registered devices. All zones: locally registered devices plus neighbor or traversal zones. Local Zone: locally registered devices only. Named: a specific zone or subzone. No "Neigbor Zone" or "Traversal Zone" is available, so the only possible correct answer is B "Any"

this wouldn't prevent toll fraud though, tricky question

Selected Answer: B For me, any seems more accurate since it also covers non-registered devices

Selected Answer: B it's B