JNCIA-DevOps Python And PyEZ — 30 Questions

Question 1

When executing raw XML RPCs via PyEZ, which THREE approaches or parameters can be used to handle or inspect the response XML? (Choose two) -> Wait, let's make it THREE since the prompt requires HALF of multi-select to be 'Which THREE'. Let's verify prompt: 'HALF use 'Which TWO', HALF use 'Which THREE'.' Total multi-select = 6. 3 use TWO, 3 use THREE. Let's make this one THREE. Which THREE approaches...

Choose an answer to begin — your selection is scored in the full session.

Accepted Answer

Using etree.tostring(response, encoding='unicode') to view raw XML text. RPC responses can be converted, queried with XPath, or printed as strings.

Answer

Using dev.rpc.to_dict() to automatically serialize all RPC outputs

Answer

Using json.loads() directly on the RPC response object

Question 2

Which PyEZ utility module should you import if you need to upgrade the Junos operating system on a remote device via a Python script?

Accepted Answer

from jnpr.junos.utils.sw import SW. The SW utility module from jnpr.junos.utils.sw is used for software installation and upgrades.

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from jnpr.junos.utils.upgrade import Upgrade

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from jnpr.junos.utils.config import Config

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from jnpr.junos.device import OS_Update

Question 3

When managing configuration changes via PyEZ Config utility, which context manager ensures that changes are automatically rolled back if an exception occurs within the block?

Accepted Answer

with Config(dev) as cu:. The 'with Config(dev) as cu:' context manager automatically handles locking, loading, committing, and rolling back on failure.

Answer

with Config(dev, mode='private') as cu:

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try: cu.lock() except: cu.rollback()

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cu.commit(rollback_on_error=True)

Question 4

You are using the PyEZ SW utility to install a new Junos image on a device. Which method parameter allows the script to automatically reboot the device after a successful installation?

Accepted Answer

reboot=True. The val parameter or reboot=True flag is typically used depending on the specific SW.upgrade() call signature. Specifically, reboot=True forces the reload.

Answer

auto_reboot=1

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reload_after_install=True

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action='reboot'

Question 5

An engineer is applying a candidate configuration using PyEZ and needs to load it from an external text file named 'interfaces.conf'. Which Config method should be used?

Accepted Answer

cu.load(path='interfaces.conf', format='text'). The load method with path and format parameters is used to load configuration text from a file.

Answer

dev.load_configuration(file='interfaces.conf')

Answer

cu.load_file('interfaces.conf')

Answer

cu.read_config('interfaces.conf')

Question 6

You need to execute a custom remote procedure call (RPC) in PyEZ to retrieve the Ethernet switching table. The tag in Junos XML API is get-ethernet-switching-table-information. How should you write this method call in Python?

Accepted Answer

dev.rpc.get_ethernet_switching_table_information(). PyEZ maps XML RPC hyphens to Python underscores, allowing you to call rpc methods directly as attributes on dev.rpc.

Answer

dev.rpc.get-ethernet-switching-table-information()

Answer

dev.get_ethernet_switching_table_information()

Answer

dev.execute_rpc('get-ethernet-switching-table-information')

Question 7

You are writing a Python script to gather operational state information from a Junos device using PyEZ. Which method should you call on an open Device instance to retrieve standard hardware and OS inventory facts into a dictionary?

Accepted Answer

dev.facts. The .facts method populates a dictionary with system inventory details such as model, serial number, and version.

Answer

dev.rpc.get_system_inventory()

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dev.gather_facts()

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dev.get_facts()

Question 8

You are writing a script that uses PyEZ to load a partial configuration merge. By default, what configuration database mode does the Config utility lock and load into?

Accepted Answer

The candidate configuration database. By default, PyEZ loads configuration changes into the candidate configuration database.

Answer

The rescue configuration database

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A private configuration database instance

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The global active configuration database

Question 9

An automation engineer is writing a Python script using Junos PyEZ to connect to a device. Which module and class must be imported to instantiate a device object representing the Junos target?

Accepted Answer

from jnpr.junos.device import Device. The Device class from the jnpr.junos module is the foundational class used in PyEZ to manage connections and sessions with Junos devices.

Answer

from jnpr.junos.rpcs import RPC

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from jnpr.junos.facts import Facts

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from jnpr.junos.utils.sw import SW

Question 10

When writing a Python script using PyEZ, how should you handle connection timeout exceptions when attempting to connect to an unreachable Junos device?

Accepted Answer

except ConnectError:. PyEZ raises ConnectError when it fails to establish a NETCONF session with the target device.

Answer

except NetconfConnectionError:

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except DeviceOpenError:

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except socket.timeout:

Question 11

What is the primary templating engine used alongside Python for generating structured Junos configuration text in network automation workflows?

Accepted Answer

Jinja2. Jinja2 is the standard Python templating engine used for rendering configuration templates.

Answer

Ansible Engine

Answer

Mako

Answer

ERB

Question 12

In a Jinja2 template designed for Junos configuration, how do you correctly output the value of a variable named 'hostname'?

Accepted Answer

{{ hostname }}. Jinja2 uses double curly braces to print or evaluate variables.

Answer

${hostname}

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{% hostname %}

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<< hostname >>

Question 13

You are rendering a Jinja2 template in Python that includes a loop over a list of VLANs. Which Jinja2 block syntax correctly iterates over a list named 'vlan_list'?

Accepted Answer

{% for vlan in vlan_list %} ... {% endfor %}. Jinja2 uses {% for item in list %} ... {% endfor %} syntax for iteration.

Answer

{{ for vlan in vlan_list }} ... {{ endfor }}

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[for vlan in vlan_list] ... [endfor]

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<% for vlan in vlan_list %> ... <% endif %>

Question 14

What is JSNAPy primarily used for in Junos network automation?

Accepted Answer

Taking operational state snapshots and verifying device health. JSNAPy (Junos Snapshot Administrator) is used to capture operational state snapshots of Junos devices and compare them to detect changes or anomalies.

Answer

Compiling Junos CLI operational commands into Python bytecode

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Performing automated firmware upgrades across clusters

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Generating static configuration templates

Question 15

You want to run a JSNAPy verification test via Python code. Which Python class should you import and instantiate to execute the snapshot comparison programmatically?

Accepted Answer

from jnpr.jsnapy import SnapAdmin. The JSNAPy class is imported from jnpr.jsnapy to execute snapshot checks programmatically.

Answer

from jnpr.jsnapy.verify import VerifyEngine

Answer

from jnpr.junos.utils.jsnapy import JSNAPy

Answer

from jnpr.jsnapy.runner import JSNAPyRunner

Question 16

When configuring a JSNAPy test file, which section defines the specific RPCs or CLI commands that should be executed to gather operational data?

Accepted Answer

command: or rpc:. The snapcheck or check configuration structure uses test definitions pointing to specific commands.

Answer

action:

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device_credentials:

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template:

Question 17

When executing an RPC call in PyEZ, what format is typically returned by default if you do not parse it into another structure?

Accepted Answer

An XML Element (lxml.etree). PyEZ RPC calls return an ElementTree object (XML Element) representing the response from the Junos device.

Answer

A JSON dictionary

Answer

A raw plain text string

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A Python list of strings

Question 18

You need to write a Python script that extracts interface status from a Junos device using PyEZ and converts the XML output directly into a Python dictionary. Which utility or function can assist with this conversion?

Accepted Answer

Using PyEZ Table and View abstractions. The XMLtoPy function from jnpr.junos.factory or standard table/view mappings helps convert XML to Python data structures.

Answer

dev.rpc.convert_to_dict()

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json.loads(dev.rpc.get_interface_information())

Answer

etree.to_dict()

Question 19

When designing a custom PyEZ Table and View mapping in Python, what configuration parameter in the YAML definition file specifies the RPC or CLI command executed to gather the raw data?

Accepted Answer

rpc:. The 'rpc' or 'command' keyword in a PyEZ Table YAML definition specifies the underlying command to run.

Answer

get-rpc:

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exec:

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command_string:

Question 20

You are writing a script that uses PyEZ to load a Junos configuration file, but you want to replace an entire hierarchy level (e.g., protocols bgp) rather than merging the changes. Which parameter should you pass to the load method?

Accepted Answer

action='replace'. The action='replace' parameter tells PyEZ to replace the specified hierarchy level in the candidate configuration.

Answer

overwrite=True

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merge=False

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mode='override'