Exam 350-901 topic 1 question 197 discussion

I choose D

In YANG modeling, "augmenting" means extending an existing model (or data tree) by adding new elements (like config parameters or containers) without modifying the original model. You have a base model, like ietf-interfaces, which defines a network interface (name, type, enabled, etc.). Then another model (e.g., ietf-ip) comes along and augments that base model to add IP configuration (like IPv4/IPv6 settings).

should be A: This document defines the YANG module "ietf-ip", which augments the "interface" lists defined in the "ietf-interfaces" module [RFC8343] with IP-specific data nodes. https://datatracker.ietf.org/doc/rfc8344/

answer is D

chatgpt: The iana-if-type is also present, which is used for specifying the type of interface (like Ethernet, software loopback, etc.), but it is not specifically augmenting the interface configuration, rather it is defining the interface type. The openconfig-interface model is not mentioned in the snippet and hence not relevant to the provided XML configuration.

B ietf-interfaces - This module contains a collection of YANG definitions for managing network interfaces. iana-if-typ - This YANG module defines YANG identities for IANA-registered interface types. ietf-ip - This module contains a collection of YANG definitions for configuring IP implementations https://github.com/YangModels/yang/blob/main/vendor/cisco/xe/1681/iana-if-type.yang https://github.com/YangModels/yang/blob/main/vendor/cisco/xe/1681/ietf-interfaces.yang https://github.com/YangModels/yang/blob/main/vendor/cisco/xe/1681/ietf-ip.yang

I asked ChatGPT and it answered A. The Ansible playbook is using the netconf_module to configure an interface using a YANG model. As part of this workflow, the ietf-interfaces and ietf-ip YANG models are used to augment the interface. - The ietf-interfaces YANG model defines the configuration and state data for network interfaces, including Ethernet, ATM, and other types of interfaces. - The ietf-ip YANG model defines the IPv4 and IPv6 addressing configuration for interfaces. - The iana-if-type YANG model defines the interface types. - The openconfig-interface YANG model is used to configure interfaces but not used in this specific example.

I would go with A as the ietf-interfaces augment the ietf-ip. This was clearly states in this video: https://www.ciscolive.com/on-demand/on-demand-library.html?search=BRKDEV-1368&search=BRKDEV-1368#/video/1636411323819002rNiV at 35:45 .. so the ietf-interfaces is augmented by the ietf-ip to include the IP leaf that is missing in the ietf-ip module.

Lost 1 hour searching. Then looked at the extract, where the answer is written between the lines. Which is to say, ip and iana get mentioned in the xml commands. So I would go with D.

B is correct: module iana-if-type { yang-version 1; namespace "urn:ietf:params:xml:ns:yang:iana-if-type"; prefix ianaift; import ietf-interfaces { prefix if; } organization "IANA"; contact " Internet Assigned Numbers Authority https://www.netconfcentral.org/modules/iana-if-type/2017-01-19

It's D. Augment are anything added through a leaf off standard. Ex: look at ietf-ip model and the first statement are an Augment interface with leaf IPV4 which means ietf-ip adds ipv4 leaf on interface list which is not standard on ietf-interfaces YANG model. Assumpting ietf-interfaces does not have any augment on its YANG model by elimination we can be sure D is correct! Source: https://www.ciscolive.com/global/on-demand-library.html?search=BRKDEV-1368#/

The answer here I think is A. The RFC7277 states tha IETF-IP augments the IETF-Interfaces. RFC 7224 states that iana-if-type imports ietf interfaces rather than augmenting it. The only yang definition that support augmentation key word is the IETF-IP model. The best fitting answer is there for A I believe. https://datatracker.ietf.org/doc/html/rfc7277 which is the RFC for IETF-IP states the following: This document defines the YANG module "ietf-ip", which augments the "interface" and "interface-state" lists defined in the "ietf-interfaces" module [RFC7223] with IP-specific data nodes, and also adds IP-specific state data. https://datatracker.ietf.org/doc/html/rfc7224 states that iana-if-type imports ietf interfaces.

I'm not sure any of these are the answer. ietf-ip definitely includes the statements for augmenting other models however neither the iana-if-type or interfaces includes the augment statement in the model. Can someone explain how they get the yang model for iana-if-type to augment the interfaces model?

The answer B seems correct. https://tools.ietf.org/html/rfc8343 3.1 seems IANA-if-type can augment interface: augment "/if:interfaces/if:interface" and in http://www.netconfcentral.org/modules/ietf-ip, seems interface augment ietf-ip: augment /if:interfaces/if:interface so it is iana-if-type augment interface and interface augment ip, then the answer should be iana-if-type and ieft-interface Not sure whether this is correct or not though...