Introduction DevNet (1)

Introduction

Welcome to the DevNet Associate (DEVASC) course. The DEVASC course is designed for people who want to learn the knowledge and skills they need to work in network programming and automation. In addition to learning basic coding and networking concepts, learners will create code using Python.

These course materials will assist you in developing the skills necessary to do the following:

• Use basic Python programming and Linux skills.
• Implement a development environment using DevNet resources.
• Use software development and design best practices.
• Create REST API requests over HTTPS to securely integrate services.
• Explain the processes and devices that support network connectivity.
• Use current technologies to deploy and secure applications and data in a cloud environment.
• Compare software testing and deployment methods in automation and simulation environments.
• Compare Cisco platforms used for collaboration, infrastructure management, and automation.

Course Overview

Welcome to the DevNet Associate course! This course will teach you the basics of software development, networking fundamentals and automation.

The industry is shifting towards automation, applications, and integrations. It is important to learn the necessary skills in order to keep up with the fast pace of technology. The modules in this course were specifically chosen to help you obtain critical job skills.

The cause of this shift in the industry is Application Programming Interfaces (APIs). We need to be more efficient in how we deploy devices, applications, networks and infrastructures. One way to do this is to eliminate repetitive manual tasks with computer automation using APIs. APIs make it possible to build automated scripts, as well as integrations that build a network between applications. This lets the applications share data, request actions to be performed, or even notify each other when a specific event happens. You will learn about APIs, their benefits, and how to troubleshoot them in the Understanding and Using APIs module.

To be able to use APIs to write scripts and build applications, you must know how to code. You need to learn the main concepts of software development and be equipped with the necessary tools to write quality code. These topics will be covered in the Software Development and Design module.

Automation and integrations through APIs cannot exist without the network. The network allows communication between applications and clients. Using APIs have helped make the network more efficient through network programmability. Network programmability is the ability to configure, monitor, and react to events in the network in real-time. It is important to learn about the basics of the network, which is discussed in detail in the Network Fundamentals module.

With the number of APIs growing in the industry and applications integrating together, it is important to understand how to secure the network and your applications to avoid incidents such as data breaches. There are different security concerns for each deployment type, so you need to know about the various modes of deployment to make the best choice for your application. More details about securing the network and your applications are discussed in the Application Deployment and Security module.

APIs have already opened the doors for automation of the network. Network automation can be taken a step further by the automated deployment of applications. You can do this with infrastructure as code. This is basically the ability to manage the infrastructure with automation, instead of manually setting up the infrastructure. You will learn more about this topic in the Infrastructure and Automation module.

The last module is Cisco Platforms and Development. This module pulls it all together in big categories, such as collaboration, compute including data centers, networking including data models, and security. Let's get started!

Why Should I Take this Module?

Why should you take this module? Because you are a NetAcad student and you know that the world of networking is changing all the time and you want to keep your knowledge and skills up to date! The newest change in networking is using code to automate many of the functions of the network. This module is intended to be a refresh of Linux and Python skills. It contains labs and quizzes to help you recall your skills.

The DevNet Associate course will teach you the necessary skills around software development, APIs, networks, automation, and security. These skills will help you stay up-to-date with the rapid changes in the industry. At the end of each module, you can test your newly acquired skills by taking the quiz assessments. Are you ready to begin?

Linux 

Linux has gained widespread use in servers, Internet of Things (IoT) devices, networking equipment, smartphones, and many other devices you may not think of as even being computers. From the home router providing your internet connection to the server this course is hosted on, it is likely that multiple Linux-powered devices are currently enabling you to read this page.

But why do you need to know about Linux? Well, for starters, remember that VM you just downloaded and installed to be your developer environment? That is a Linux-based virtual machine. All of the coding labs in this course are performed on a Linux-based VM.

1. What Linux command is used to display the contents of the current directory?

   Topic 1.2.0 - The Linux ls command, without any options, is used to display the contents, such as files and subdirectories, of the current directory.

   pwd

   cat

   ls

   ln

2. What command is used to rename a file in a Linux system?

   Topic 1.2.0 - The mv Linux command can be used to move a file to another directory or rename a file. The cp command is used to make a copy of files or directories. The dd command is also used to make a copy of a file. The rm command is used to delete a file.

   cp

   mv

   dd

   rm

3. A user issues a Linux command and the result is shown.

   total 40
   drwxr-xr-x 2 devasc devasc 4096 Apr 15 19:09 Videos
   drwxr-xr-x 2 devasc devasc 4096 Apr 15 19:09 Templates
   drwxr-xr-x 5 devasc devasc 4096 Mar 30 21:24 snap
   drwxr-xr-x 2 devasc devasc 4096 Apr 15 19:09 Public
   drwxr-xr-x 2 devasc devasc 4096 Apr 15 19:09 Pictures
   drwxr-xr-x 2 devasc devasc 4096 Apr 15 19:09 Music
   drwxr-xr-x 5 devasc devasc 4096 Mar 30 21:21 labs
   drwxr-xr-x 2 devasc devasc 4096 Apr 15 19:09 Downloads
   drwxr-xr-x 2 devasc devasc 4096 Apr 15 19:09 Documents
   drwxr-xr-x 2 devasc devasc 4096 Mar 30 21:25 Desktop
   devasc@labvm:~$

   Which Linux command is used to display the contents of the current directory as shown?

   Topic 1.2.0 - The Linux ls command with the -l option is used to display contents in the current directory as a “long list”. By default, the listing is sorted alphabetically. With both the -l and -r options specified, the listing is displayed as a long list and in reverse order.

   ls -l

   ln

   ls -a

   ls -lr

4. A system administrator of a Linux server is searching the passwd file for the username taylor that appears at the beginning of the line. Which grep command should the administrator use?

   Topic 1.2.0 - The Linux grep command can be used to process text line by line and to print any lines which match a specified pattern. The matching patterns are based on regular expression (regex) query modifiers used to select the appropriate content. Some regex query modifiers are as follows:

   •   (underscore):  matches a space
   • ^ (caret): indicates the start of a string
   • $ (dollar sign): indicates the end of a string
   • . (period): matches a single character, including a space
   • • (asterisk): matches zero or more occurrences of the preceding character
   •  (square bracket): matches a character
   • { } (curly bracket):  repeats preceding character

   grep taylor /etc/passwd

   grep '^taylor' /etc/passwd

   grep '[taylor]' /etc/passwd

   grep '.taylor' /etc/passwd

5. A user issues the apt-get upgrade command to update system files in a Ubuntu Linux system and receives an error message of "permission denied." What should the user do to complete the task?

   Topic 1.2.0 - There are several Linux commands in the Advanced Package Tool (APT) system to perform software package management tasks. The apt-get upgrade command is used to update all packages and dependencies on the system. This command must be run with administrative level permissions, which are provided by the sudo command.

   Issue the sudo apt-get upgrade command.

   Issue the allow apt-get upgrade command.

   Issue the apt-get install --allow command.

   Issue the sudo apt-get install command.

Python 

Python Programming

Python is an easy to learn programming language that you will use throughout this course. Why should you learn Python? You will need to become familiar with basic Python to complete many of the labs in this course. In addition to this, the Python Essentials course (see the link in Student Resources) names a few factors that make Python a great tool for learning basic coding:

• It is easy to learn - the time needed to learn Python is shorter than for many other languages; this means that it's possible to start the actual programming faster.
• It is easy to use for writing new software - it's often possible to write code faster when using Python.
• It is easy to obtain, install and deploy - Python is free, open and multiplatform; not all languages can boast that.
• If you're not familiar with any other languages, Python is great to begin with, because it will give you a solid foundation and allow you to learn other programming languages (e.g., C++, Java, or C) much easier and much faster. Learning Python is fun and trendy!

Quiz - Python Review

1. A student is learning Python using the interactive interpreter mode. The student issues the commands:

   >>> routers=[]
   >>> switches=[]
   >>> devices=[\"RT1\", \"RT2\", \"RT3\", SW1\", \"SW2\", \"SW3\"]
   >>> devices=devices + [\"RT4\", \"SW4\"]
   >>> for i in devices:
                if \"R\" in i:
                       routers.append(i)
                else: switches.append(i)
   >>> switches  
   

   What is the result?

   Topic 1.3.0 - In Python, two lists can be concatenated by using the + (plus sign) operator. The second list appends to the first list and makes a new list. The Python for function is used to loop through the elements in a list and perform an operation on an element. The if statement can be used within the for function to determine the proper action based on the matching condition of each element.

   ['SW4']

   ['SW1', 'SW2', 'SW3']

   ['SW4', 'SW3', 'SW2', 'SW1']

   ['SW4', 'SW1', 'SW2', 'SW3']

   ['SW1', 'SW2', 'SW3', 'SW4']

2. A student is learning Python in the interactive interpreter mode. The student issues the commands:

   >>> devicenames=[\"RT1\", \"RT2\", \"SW1\", \"SW2\"]
   >>> devicenames[-1]  
   

   What is the result?

   Topic 1.3.0 - In Python, an item in a list can be referenced and manipulated using its index. The first item in a list is indexed as zero, the second is indexed as one, and so on. The last item can also be referenced with an index of [-1].

   ['RT2', 'SW1', 'SW2']

   RT1

   an error message

   SW1

   SW2

3. A developer needs to check the version of the running Python package. Which command should the developer use?

   Topic 1.3.0 - The command python3 starts Python, but adding the -V option displays the specific version being used. 

   python3 -V

   python3 --v

   python3 -q

   python3 -i

4. A student is learning Python in the interactive interpreter mode. The student issues the command:

   >>> type(True)  
   

   What is the data type reported by Python?

   Topic 1.3.0 - A type of True or False is a predefined value of the Boolean data type.

   string

   Boolean

   float

   integer

5. Which Python programming function is used to display output?

   Topic 1.3.0 - Print is used to display output in a Python programing language interpreter.

   if

   while

   for

   print

Course Introduction Summary 

 This Course Introduction module was designed to help you prepare to take the DevNet Associate (DEVASC) course. The Install the Virtual Lab Environment gets you and your PC ready for the many coding labs you will find in this course. The Linux Review and Python Programming Review labs help you to determine whether you are ready with the prerequisite knowledge and skills required to successfully take the DEVASC course.

Ref : [1]

Modul Exam 1

A student new to Python is working in the interactive interpreter mode. The student issues the commands:

                          
>>> ipAddress = {"R1":"10.1.1.1","R2":"10.2.2.1","R3":"10.3.3.1"}
                          
                        

Which data type is used to represent the variable ipAddress?

• tuple
• list
• dictionary
• array
• A Linux system administrator is searching the passwd file for any username that starts with a digit. Which grep command should the administrator use?
  • grep '_[0-9]' /etc/passwd
  • grep '{0-9}' /etc/passwd
  • grep '[0-9]' /etc/passwd
  • grep '^[0-9]' /etc/passwd
• A user enters the commands as shown. What is the result after the mv command is entered?
  
  devasc@labvm:~/Documents$ pwd
  /home/devasc/Documents
  devasc@labvm:~/Documents$ mv myfile.sh ../Desktop/myfile2.sh
  • The file myfile.sh is copied to the /home/devasc/Desktop directory and replaces the file myfile2.sh.
  • The file myfile.sh is copied and renamed to myfile2.sh in the current directory.
  • The file myfile.sh is moved to the /home/devasc/Desktop directory and renamed as myfile2.sh.
  • The file myfile.sh is copied to the /home/devasc/Desktop directory and renamed as myfile2.sh.
• A user issues a series of Linux commands as shown.
  
  (omitted)$ pwd
  /home/devasc/labs/ansible/backups
  (omitted)$ cd ../..
  
  Which directory is the current directory after the cd command is entered?
  • /
  • /home
  • /home/devasc/
  • /home/devasc/labs
  • /home/devasc/labs/ansible
• A student is learning Python and is reviewing a Python script as follows:
  

                            
  aclNum = int(input("What is the IPv4 ACL number? "))
  if aclNum >= 1 and aclNum <= 99:
       print("This is a standard IPv4 ACL.")
  elif aclNum >=100 and aclNum <= 199:
       print("This is an extended IPv4 ACL.")
  else:
       print("This is not a standard or extended IPv4 ACL.")
                            
                          

  Under which condition will the elif  statement be evaluated?
  • when the input is a string
  • when the first print statement fails
  • when the input is a float number
  • when the if statement is false
  • A network engineer needs to review the status of all network interfaces of a server running a Linux operating system. The engineer enters the command ifconfig -a . What is the result of this command?
    • The ARP table of the computer will be displayed.
    • All active interfaces will display information.
    • The host routing table will be displayed.
    • Both active and inactive interfaces will display information.
    • A student is learning Python in the interactive interpreter mode. The student issues the commands:
      

                                
      >>> y=2
      >>> y*3
      6
      >>> 'Test'*y
                                
                              

      What is the result?

      • 'TestTest'
      • 'Test6'
      • 'Test2'
      • 'TestTestTestTestTestTest'
      • TypeError: A string type cannot be multiplied by an integer.
      What is the output when the following code is entered into a Python program interpreter?
      
      [1,2,4,5] + [3,6]
      

      • [12]+[9]
      • [21]
      • [1,2,4,5,3,6]
      • [1,2,3,4,5,6]
      • A student new to Python is working in the interactive interpreter mode. The student issues the commands:
        

                                  
        >>> devicenames=["RT1", "RT2", "SW1", "SW2"]
        >>> hostnames=devicenames + ["RT3", "SW3"]
        >>> del hostnames[3]
        >>> hostnames
                                  
                                

        What is the result?
        • ['RT1', 'RT2', 'RT3', 'SW2', 'SW3']
        • ['RT1', 'RT2', 'SW2', 'RT3', 'SW3']
        • ['RT1', 'RT2', 'SW1', 'RT3', 'SW3']
        • ['RT1', 'RT2', 'SW1', 'SW2', 'SW3']
        • What is displayed after the following code is entered into a Python interpreter?
          
          addition = 22 +10
          print(addition)
          
          • [22]+[10]
          • (syntaxerror)-...as there should not be a space between the numerical values
          • 32
          • nothing ( because the print command is wrong)
          • A Linux administrator is attempting to use a terminal to configure the network interface card on a computer. The administrator receives a message that the administrator does not have necessary permissions to perform the configuration. What should be done prior to the configuration command?
            • identify a different network interface
            • change the chmod permissions on the network configuration file
            • use a different user account
            • use the sudo command
            • A student new to Python is working in the interactive interpreter mode. The student issues the command:
              

                                        
              >>> ipAddress = {"R1":"10.1.1.1","R2":"10.2.2.1","R3":"10.3.3.1"}
                                        
                                      

              Which Python expression can be used to retrieve the IP address of R2?
              • ipAddress[R2]
              • ipAddress{"R2"}
              • ipAddress['R2']
              • ipAddress{'R2'}
              • A system administrator attempts to determine what is causing a computer to perform slower than normal. The administrator issues the ps command. What is displayed by this command?
                • active processes using CPU time
                • current NIC status
                • current HDD usage
                • current RAM usage
                • A user issues the Linux command ls -l myfile.sh to check the permission of the file myfile.sh.
                  
                  devasc@labvm:~/Documents$ ls -l myfile.sh
                  -rwxr-xr-- 1 self test 15 Mar 30 21:24 myfile.sh
                  
                  Which two statements describe the permissions assigned to the file? (Choose two.)
                  • Any user in the test group can execute the file.
                  • The user with the user ID of devasc can modify the file.
                  • Any user in the self group can read, modify, and execute the file.
                  • All users can execute the file.
                  • The user with the user ID of self can modify the file.
                  • Which Python command creates a conditional control structure?
                    • if
                    • delay
                    • from
                    • def
                    • A system administrator issues the apt-get upgrade command on a Linux operating system. What is the purpose of this command?
                      • A specific application named upgrade will be installed.
                      • Operating system updates are downloaded and will be installed.
                      • The remote repository of applications and dependencies will be updated to the latest version.
                      • Every application installed will update itself to the latest version.
                      • A user issues a Linux command and the result is shown:
                        
                        total 40
                        drwxr-xr-x 2 devasc devasc 4096 Mar 30 21:25 Desktop
                        drwxr-xr-x 2 devasc devasc 4096 Apr 15 19:09 Documents
                        drwxr-xr-x 2 devasc devasc 4096 Apr 15 19:09 Downloads
                        drwxr-xr-x 5 devasc devasc 4096 Mar 30 21:21 labs
                        drwxr-xr-x 2 devasc devasc 4096 Apr 15 19:09 Music
                        drwxr-xr-x 2 devasc devasc 4096 Apr 15 19:09 Pictures
                        drwxr-xr-x 2 devasc devasc 4096 Apr 15 19:09 Public
                        drwxr-xr-x 5 devasc devasc 4096 Mar 30 21:24 snap
                        drwxr-xr-x 2 devasc devasc 4096 Apr 15 19:09 Templates
                        drwxr-xr-x 2 devasc devasc 4096 Apr 15 19:09 Videos
                        devasc@labvm:~$
                        
                        Which Linux command is used to display the contents of the current directory as shown?
                        • ls -lr
                        • ls -a
                        • ls -l
                        • ls