DevNet Associate (200-901) Certification Practice Test Online

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RPC, SOAP, and REST are the three most popular types of API architectural styles. They all support the client-server model. RPC and REST can use XML or JSON. SOAP uses XML. REST requires that the communication between the client and the server remains stateless.

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With REST APIs, the response code 201 is with the status message of “Created”. It indicates that the request was fulfilled, and the requested resource was created.

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The error message indicates that the connection to the host cannot be established. The causes could be an internet connection issue, or the domain name of the host cannot be resolved by DNS servers because it is wrong.

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Common types of REST API authentication mechanisms include Basic, Bearer, and API Key. Basic authentication uses the standard Basic HTTP authentication scheme by specifying credentials such as username/password pairs. The username is in plain text and the password is encoded using Base64.

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A webhook is an HTTP callback, or an HTTP POST, to a specified URL that notifies a registered application when an activity or event has occurred in one of the resources on the platform. Webhooks enable applications to get real-time data. With webhooks, applications are more efficient because they no longer need to have a polling mechanism.

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When the scheme of the REST API call URL is HTTPS, the connection will perform an SSL handshake between the client and the server with a Certificate Authority (CA). This handshake needs to be successful before the REST API request is even sent to the API server. The SSL handshake could fail if the certificate is invalid or it is self-signed. A user can specify if the SSL verification should be avoided by specifying “verify = False” as a parameter to the Python requests module, requests.get() method. The default is “verify = True”.

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The HTTP header string is a cache control directive that indicates that (1) the response content can be saved by any cache and (2) the cached content will expire in 3600 seconds unless it gets refreshed before it expires.

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The script will test for an invalid URI condition if the verify parameter is set to False.

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Yet Another Next Generation (YANG) is a standards-based data modeling language. NETCONF is a standards-based protocol designed to retrieve the information of network devices and to manage devices. Extensible Markup Language (XML) is an encoding protocol that provides the transport for NETCONF to communicate with devices using the YANG formatted configuration or operational data. An application that runs on a centralized management platform or laptop/desktop can use NETCONF to send requests to a network device for information or to make configuration changes.

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• Service Manager: maintains device dependencies and provideds a service self start for triggering diagnostic tests
• Device Manager: deploys configuration changes to multiple devices through the use of distributed transactions
• Configuration Database: provides an internal API for locating network element configurations and automatic support for upgrade and downgrade of configuration data

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Ansible uses an inventory file called hosts that contains device information used by Ansible playbooks. The hosts file begins with an alias for the remote. After the alias, the hosts file specifies three variables that will be used by the Ansible playbook to access the device. These are the SSH credentials Ansible needs to securely access the remote host. The error message indicates that the SSH server on the destination host cannot be reached. The possible issue is either the SSH server is not running or the IP address configured in the hosts file is wrong.

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Continuous Integration/Continuous Deployment (CI/CD) is a philosophy for software development that includes automation as part of the process. Continuous integration attempts to eliminate the problem of conflicts that occur when new or updated code is applied to the main application. Even though there is a potential of a bad build being deployed to the users, companies can limit that impact by using a deployment strategy such as a rolling upgrade, canary pipeline, or blue-green deployment.

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In a formal code review, developers have a series of meetings to review the whole codebase and go over the code line by line, discussing each one in detail. The formal code review process promotes discussion among all of the reviewers.

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In summary, model-driven programmability does the following:

• Provides configuration language that is human-readable
• Is model-based, structured, and computer-friendly
• Includes support for multiple model types, including native, OpenConfig, and IETF
• Uses a specification that is decoupled from transport, protocol end encoding
• Uses model-driven APIs for abstraction and simplification
• Leverages open-source and enjoys wide support

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Continuous Integration/Continuous Deployment (CI/CD) is a philosophy for software development that includes automation as part of the process and integrates with Agile development strategies. Application development occurs in small chunks and allows users to receive incremental changes, making it easier for adaptation to new software and reducing disruption.

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Ansible uses an inventory file called hosts that contains device information used by Ansible playbooks. The hosts file begins with an alias for the remote. After the alias, the hosts file specifies three variables that will be used by the Ansible playbook to access the device. These are the SSH credentials Ansible needs to securely access the remote host.

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PyATS uses Python for low-level code, but relies on Genie, a higher-level library system, in order to interact with network devices and perform testing.

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The job of a forward proxy is to make requests from multiple computers look like they all come from the same client. This is the opposite of a reverse proxy, which makes sure responses look like they all come from the same server.

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The CI/CD (Continuous Integration and Continuous Delivery) pipeline is a software deployment philosophy that provides for a process of automated testing and deployment.

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The nslookup command is available on nearly all operating systems. It is used for querying the Domain Name System (DNS) in order to obtain domain name to IP address mapping.

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Bare metal deployment installs software directly on host hardware and provides applications with direct access to host hardware resources. This is more efficient and increases performance.

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The term edge computing refers to the practice of placing computing resources as close the actual sources of data as possible.

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This item is based on information contained in the presentation. A DoS (denial of service) attack prevents users from accessing network resources. A brute force attack attempts to guess the password of an account. A zero day attack is the first occurrence of a previously unknown virus or other malware.

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DevNet provides ways for community members to share with each other. These are called Exchanges. In the Code Exchange site, users can submit a repository that they have found useful for any technology area. Users can search for any keyword in the repository and get a list of results.

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The Meraki enterprise cloud-managed networking infrastructure service has five different APIs for integration:

• Dashboard API: This a RESTful service for device provisioning, management, and monitoring.
• Webhook API: This is a real-time notification system for network alerts, covering events and network health.
• Location Streaming API: This is an HTTP POST method providing Wi-Fi and Bluetooth client location information (GPS, X/Y coordinates) based on Meraki Access Point (AP) map placement and client signal strength.
• External Captive Portal (EXCAP) API: This enables an organization to build out custom engagement models at Wi-Fi access points.
• MV Sense API: This is a combination of REST APIs and real-time MQTT stream supporting oversight of a physical space.

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The Cisco UCS Manager products provide scalability by integrating many components of a data center. The different management products directly relate to the number of servers being managed:

• Cisco Integrated Management Controller (CIMC) can manage a single physical server.
• Cisco UCS Manager (UCSM) can manage up to 160 physical servers.
• Cisco UCS Central (UCSC) can manage up to 10,000 physical servers.

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Cisco IOS XE is the next-generation programmable platform. Both NETCONF and RESTCONF are supported. Their connections should be authenticated using AAA credentials. RESTCONF runs over HTTPS which is enabled by the command ip http secure-server . The CLI command to enable RESTCONF is simply restconf . NETCONF uses SSH as a transport. NETCONF supports both running and candidate data stores, whereas RESTCONF supports only a running datastore.

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User Data Services (UDS) is a REST-based API that provides a mechanism for inserting, retrieving, updating, and removing data from the Unified Communication configuration database. The UDS API is designed to enable end users to update and configure personal settings.

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When a Git merge is performed, the source branch is untouched and only the target branch is modified.

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With the Test-Driven Development process, testing code is written before application code. The application code is then created with the single purpose of being able to barely pass the testing code.

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The distributed version control system is a peer-to-peer model that clones the full repository to client systems and allows every individual to work on any file, even at the same time.

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The XML prologue is placed as the first line in an XML file and contains the tag name xml and attributes that provide the version and the character encoding.

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Parsing is the process of analyzing a message, separating it into component parts, and understanding the purpose of it in context.

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With the IPv4 address, a subnet mask is also necessary. A subnet mask is a special type of IPv4 address that coupled with the IP address determines the subnet of which the device is a member.

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The nslookup command is used to obtain an IP address for a specific domain name by querying a DNS server. The desired domain name follows the command and optionally the IP address of a particular DNS server.

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If the connection fails when using Cisco AnyConnect to connect to the DevNet Sandbox, check login credentials for any typing errors, the VPN URL of the DevNet Sandbox, and clear the Block Untrusted Connections option in the AnyConnect preferences.

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Because server load balancing distributes server requests across multiple servers, the load balancer should be attached to the same switch that the servers are on.

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A virtual local-area network (VLAN) is a separate Layer 2 network that has its own broadcast domain. A Layer 3 device such as a router or multilayer switch is required to communicate between VLANs.

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Name resolution issues often manifest as lost network connectivity and authentication failures between a network app and a remote server. Common problems include defining the correct DNS server, a missing or incorrect DNS entry, an incorrect hostname, or a configuration issue on the DNS server being used.

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All Ethernet network devices have a unique Media Access Control (MAC) address that is burned into the network interface card (NIC). The MAC address is used to direct data from a particular device to a specific network destination.

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Telnet commonly uses 23 or 992 whereas the secure protocol SSH uses port 22. DNS uses port 53. HTTP uses port 80 and HTTPS uses 443. NETCONF uses port 830. RESTCONF can use ports 8008, 8080, or 8888.

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A container is an isolated environment where containerized applications run. It contains the application and all dependencies needed for the application to run. The containers on a physical server all share the same OS, are isolated from each other, and leverage the kernel of the host operating system to allow for quick starts.

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The term edge computing refers to the practice of placing computing resources as close to the actual sources of data as possible. Deploying computer resources at the edge, can help to avoid high levels of data transfer across the network for performance or security purposes.

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Bash is the name of the default script engine that lets you do things from the command line. It is the default shell for most Linux distributions.

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Network Address Translation (NAT) is a technology that is implemented within IPv4 networks. One application of NAT is to use private IP addresses inside a network and use NAT to share a few public IP addresses for many internal hosts. In this way it provides a solution to slow down the IPv4 address depletion. However, since NAT hides the actual IP addresses that are used by end devices, it may cause problems for some applications that require end-to-end connectivity.

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A switch builds a MAC address table of MAC addresses and associated port numbers by examining the source MAC address found in inbound frames. To forward a frame onward, the switch examines the destination MAC address, looks in the MAC address for a port number associated with that destination MAC address, and sends it to the specific port. If the destination MAC address is not in the table, the switch forwards the frame out all ports except the inbound port that originated the frame.

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If a large amount of return data is expected, the client can request that the return data be compressed with a specific compression algorithm. To request a data compression, the request must add the Accept-Encoding field to the API request header. For example, a header string of “Accept-Encoding: gzip” tells the server to compress the return data using the gzip algorithm. If the server fulfills the compression, it will send the response back with the compressed data and add the Content-Encoding field to the response header. The value of the Content-Encoding is the type of compression that was used.

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Cisco Umbrella serves as a first line of defense for an organization by blocking requests to malicious internet destinations.

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Cisco VIRL is used to build network simulations and it can duplicate the same code that runs inside actual Cisco products. The native configuration format is called a.virl file, which is a human-readable YAML file.

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Continuous Delivery is the process of developing in sprints that are short enough so that the code is always in a deployable state. With Continuous Integration, small change sets are continuously integrated into the main code branch. Continuous Delivery means that those changes are engineered to be self-contained to the point where at any given time, you could deploy a working application.

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Containers provide many of the same benefits as VMs, such as workload isolation and the ability to run multiple workloads on a single machine, but a container shares the operating system of the host machine and uses container-specific binaries and libraries. Docker is a popular container engine.

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Load balancing distributes server requests across multiple servers. The load balancer selects which server receives the client request and provides connectivity to device redundancy, high availability, and scalability.