The correct answer is B. TLS or SSL for communication.
In basic API authentication, credentials (such as username and password) are often transmitted using Base64 encoding, which is not encrypted. This makes them vulnerable to sniffer (packet capture) attacks if sent over an unencrypted channel.
* TLS (Transport Layer Security) and its predecessor SSL provide encryption of the communication channel.
* This ensures that even if packets are captured, the credentials remain confidential and unreadable.
* Cisco documentation emphasizes that APIs (RESTCONF, HTTP-based APIs) should use HTTPS (HTTP over TLS) to secure credentials in transit.
* A. VPN connection between client and server While a VPN encrypts traffic, it is not specifically required for API authentication security. The standard and expected method is TLS/HTTPS.
* C. AAA services to authenticate the API AAA controls who can access, but it does not encrypt credentials in transit.
* D. next-generation firewall A firewall provides traffic filtering and threat protection but does not directly secure credential transmission in basic API authentication.
* Basic Authentication = NOT secure by itself
* Always pair it with HTTPS (TLS encryption)
Rule to remember:
If credentials travel over the network # encrypt with TLS

Next-generation firewalls extend traditional firewall behavior by adding deeper traffic inspection and application-level intelligence. Packet filtering, stateful inspection, and VPN support existed before NGFWs and are not unique to them. Traditional firewalls can permit or deny traffic based on source IP, destination IP, protocol, port, and connection state. NGFWs add the ability to inspect application payloads more deeply, identify applications even when they use nonstandard ports, apply policy based on application identity, detect threats inside permitted sessions, and integrate IPS or malware inspection. Therefore, deep packet inspection and application awareness are the best answers. Deep packet inspection allows the firewall to examine packet contents beyond simple Layer 3 and Layer 4 headers. Application awareness allows policy to distinguish, for example, legitimate HTTPS business traffic from risky file-sharing, tunneling, or unauthorized application traffic over the same port. VPN is useful but not unique to NGFWs. Stateful inspection is also a core feature of earlier stateful firewalls.
References/topics: ENCOR Security, next-generation firewall, application visibility, deep packet inspection, IPS, advanced threat protection.

The correct answers are B. rpc statements and E. container statements.
YANG is a data modeling language used to model configuration and operational data for protocols such as NETCONF and RESTCONF. In YANG, the model is built using defined language statements such as container, list, leaf, and rpc. Cisco documentation explains that actions are defined in YANG models using RPC statements, and the YANG language definition identifies container as a standard statement used to define an interior data node in the schema tree.
Cisco documentation states that YANG models can define operational actions using RPC statements. These are used to trigger operations such as commands or actions on the device.
A container is one of the fundamental building blocks of a YANG model. It represents an interior node in the hierarchical data tree and is commonly used to group related configuration or state data.
* A. HTTP return codes These belong to HTTP-based protocol behavior, not to the YANG model language itself.
* C. JSON schema YANG is not a JSON schema language. Although YANG data may be encoded in JSON for some APIs, JSON schema is not a YANG model element. Cisco notes that protocols may use JSON formatting, but that does not make JSON schema part of YANG.
* D. XML schema YANG is its own modeling language. NETCONF commonly uses XML encoding, but XML schema itself is not one of the YANG language statements.
ENCOR exam point:
Know the difference between:
* YANG model elements # container, list, leaf, rpc
* Data encodings / transport formats # XML, JSON
* Protocol behaviors # HTTP status codes, NETCONF operations