Cisco Updated 350-701 Exam Questions and Answers by finnian

NTP uses UDP port 123 to communicate with its servers and peers. If the Cisco ASA has IP reachability to the NTP server and is not filtering any traffic, then the most likely cause of the unsynchronized state and the stratum of 16 is that the NTP server is not working properly or is not configured to provide NTP service. A stratum of 16 means that the NTP server is unreachable or is not considered a viable candidate1. The value.INIT. in the refid column indicates that NTP is initializing, and the server has not yet been reached1. To resolve this issue, the network engineer should verify the status and configuration of the NTP server, and use a different server if needed. Alternatively, the network engineer can use the ntp server command with the prefer keyword to specify a preferred NTP server, or use the ntp update-calendar command to force a resynchronization of NTP2. References:

1: NTP server is unsynchronized or unreachable, a Wireshark perspective.

2: Implementing and Operating Cisco Security Core Technologies (SCOR) v1.0, Module 1: Network Security, Lesson 1.3: Configuring Network Time Protocol.

Northbound APIs are the link between the applications and the SDN controller. The applications can tell the network what they need (data, storage, bandwidth, and so on) and the network can deliver those resources, or communicate what it has. These APIs support a wide variety of applications, such as load balancers, firewalls, orchestration platforms, and automation stacks. Northbound APIs also enable the applications to use the controller’s capabilities to program flows into the network devices using the southbound interface. Northbound APIs are usually RESTful APIs that use HTTP methods to exchange data in JSON or XML formats12.

OpenFlow is not a northbound API protocol, but a southbound API protocol that defines the communication between the SDN controller and the network switches or routers. OpenFlow allows the controller to manipulate the forwarding behavior of the switches or routers by sending commands and receiving events3 .

NETCONF is not a northbound API protocol, but a network management protocol that can be used as a southbound API protocol to configure and monitor network devices. NETCONF uses XML to encode data and remote procedure calls (RPCs) to exchange messages between the controller and the network devices . References := 1: What are SDN Northbound APIs (and SDN Rest APIs)? - SDxCentral 2: SDN North-bound and South-bound APIs and Interfaces 3: OpenFlow - Wikipedia : OpenFlow - SDxCentral : NETCONF - Wikipedia : NETCONF Protocol - Cisco

1sdxcentral.com2computernetworkingnotes.com3examguides.com

Cisco DNA Center is an open and extensible platform that allows third-party applications and processes to exchange data and intelligence with Cisco DNA Center1. One of the features of the open platform capabilities of Cisco DNA Center is the intent-based APIs, which enable DNA Center to provide automation to applications2. Intent-based APIs allow applications to express their intent or desired outcome, and let DNA Center translate that intent into network configurations and policies3. Intent-based APIs simplify the interaction between applications and the network, and enable faster and more consistent service delivery.

 1: Cisco DNA Center 2.3.5 Data Sheet - Cisco 2: Intent-Based Networking’s Next Evolution: The DNA Center Platform - Cisco Blogs 3: Unlocking the Power of Open Platforms with Cisco DNA Center Platform