350-601 Question #409: Real Exam Question with Answer & Explanation

Question

An engineer implements a Python script inside a Cisco Bash shell. The script contains this dictionary object: Which command must be used to add the 'NSK-Spine-2': `1498323434' element to the switch_id list dictionary?

Options

• Aswitch_id_list += {"N9K-Spine-2": "1498323434"}
• Bswitch_id_list = ["N9K-Spine-2": "1498323434"]
• Cswitch_id_list.append({"N9K-Spine-2": "1498323434"})
• Dswitch_id_list.update({"N9K-Spine-2": "1498323434"})

Explanation

To add a new key-value pair to an existing Python dictionary named switch_id_list, the update() method is the correct approach for merging the new dictionary element.

Common mistakes.

• A. The += operator is not used for merging dictionaries in this manner; it typically performs in-place addition for lists or concatenation for strings, and would result in a TypeError for dictionaries.
• B. Assigning a new dictionary using = would overwrite the existing switch_id_list dictionary, not add an element to it, and the syntax ["N9K-Spine-2": "1498323434"] is incorrect for creating a dictionary.
• C. The append() method is used to add an item to the end of a list, not to merge elements into a dictionary. If switch_id_list were a list, append would be applicable, but the question states it's a dictionary object.

Concept tested. Python dictionary manipulation (update method)

Reference. https://docs.python.org/3/library/stdtypes.html#dict.update

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