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ServiceNow REST API Interview 2024

Q: What is the purpose of the Inbound REST API in ServiceNow?
A:
The Inbound REST API allows external systems to perform operations on ServiceNow resources, such as creating, reading, updating, and deleting records.

Q: Describe the authentication methods available for the ServiceNow REST API.
A:
ServiceNow supports several authentication methods, including Basic Authentication, OAuth 2.0, and Mutual Authentication (mTLS).

Q: What is Basic Authentication, and how is it used in ServiceNow REST API requests?
A:
Basic Authentication uses a username and password encoded in Base64. It is included in the HTTP header of the request to authenticate the user.

Q: Explain OAuth 2.0 and its use in ServiceNow.
A:
OAuth 2.0 is an authorization framework that allows applications to obtain limited access to user accounts on an HTTP service. ServiceNow supports OAuth 2.0 for secure API access without exposing user credentials.

Q: What are the HTTP methods supported by ServiceNow’s REST API?
A:
The supported HTTP methods include GET, POST, PUT, PATCH, and DELETE.

Q: How can you retrieve a specific record using the REST API in ServiceNow?
A:
Use the GET method with the specific record’s Sys ID in the URL endpoint to retrieve a specific record.

Q: What is a REST message, and how is it configured in ServiceNow?
A:
A REST message is a ServiceNow resource that defines the HTTP method, endpoint, and authentication for a REST API call. It is configured in the REST Message module.

Q: Explain the purpose of query parameters in REST API requests.
A:
Query parameters are used to filter and refine the data returned by a REST API request. They are appended to the URL.

Q: How do you handle pagination in ServiceNow REST API responses?
A:
Pagination is managed using the sysparm_limit and sysparm_offset parameters to control the number of records returned and the starting point of the records.

Q: What is the difference between PUT and PATCH methods in the REST API?
A:
The PUT method updates a resource by replacing it with the request payload, while the PATCH method updates only the specified fields of a resource.

Q: Describe how to create a new record using the REST API.
A:
Use the POST method with the appropriate endpoint and include the record data in the request body to create a new record.

Q: How do you update an existing record using the REST API?
A:
Use the PUT or PATCH method with the specific record’s Sys ID in the URL endpoint and include the updated data in the request body.

Q: Explain the DELETE method in the context of ServiceNow’s REST API.
A:
The DELETE method is used to remove a specific record from the ServiceNow database by specifying its Sys ID in the URL endpoint.

Q: What is the role of the sysparm_fields parameter in REST API requests?
A:
The sysparm_fields parameter specifies which fields should be returned in the response, reducing the amount of data transferred.

Q: How can you ensure secure communication between a client and the ServiceNow REST API?
A:
Ensure secure communication by using HTTPS and implementing OAuth 2.0 or Mutual Authentication (mTLS).

Q: What are REST API Rate Limits in ServiceNow?
A:
Rate limits control the number of API requests that a user can make within a specified time period to prevent abuse and ensure system stability.

Q: How do you configure a REST API rate limit in ServiceNow?
A:
Rate limits are configured in the System Web Services > REST API Rate Limits module by defining the rate limit rules for different users or roles.

Q: Describe the process of handling errors in REST API responses.
A:
Errors are handled by checking the HTTP status code in the response. ServiceNow provides specific error codes and messages to indicate the nature of the problem.

Q: What is the sysparm_query parameter used for in a GET request?
A:
The sysparm_query parameter is used to filter records based on encoded query strings, similar to how filters work in ServiceNow.

Q: Explain the concept of a Scripted REST API in ServiceNow.
A:
Scripted REST APIs allow developers to create custom REST endpoints and implement server-side scripts to define the behavior of these endpoints.

Q: How do you define a Scripted REST API in ServiceNow?
A:
Scripted REST APIs are defined in the Scripted REST APIs module by creating a new API and defining resources and HTTP methods with associated scripts.

Q: What is the glide.rest.enable_api_explorer property?
A:
This property enables the REST API Explorer, a tool for testing and exploring available REST APIs in ServiceNow.

Q: How can you test REST API calls within ServiceNow?
A:
Use the REST API Explorer or tools like Postman to test REST API calls by sending requests to ServiceNow endpoints.

Q: What is the purpose of the REST API Explorer?
A:
The REST API Explorer helps users test and explore the available REST APIs, including creating, updating, and deleting records.

Q: Describe how to use the REST API Explorer to create a new record.
A:
Select the appropriate table, choose the POST method, and provide the necessary fields and values in the request body to create a new record.

Q: What is the Accept header in a REST API request?
A:
The Accept header specifies the format of the response data, such as application/json or application/xml.

Q: How do you handle authentication tokens in ServiceNow REST API?
A:
Authentication tokens, such as OAuth tokens, are included in the HTTP header of the request to authenticate API calls.

Q: What are the benefits of using OAuth 2.0 over Basic Authentication?
A:
OAuth 2.0 provides enhanced security by allowing limited access without exposing user credentials and supports token-based authentication.

Q: Explain the Content-Type header in REST API requests.
A:
The Content-Type header indicates the format of the request body, such as application/json for JSON data.

Q: How do you configure mutual authentication (mTLS) for the REST API in ServiceNow?
A:
Mutual authentication is configured by uploading client certificates and configuring the API to require these certificates for access.

Q: What is a REST endpoint in the context of ServiceNow?
A:
A REST endpoint is a specific URL where API requests are sent to interact with ServiceNow resources.

Q: Describe how to use the sys_id parameter in a REST API request.
A:
The sys_id parameter is used to specify a unique identifier for a record when performing operations such as retrieving, updating, or deleting.

Q: What is the purpose of the sysparm_display_value parameter?
A:
The sysparm_display_value parameter determines whether to return the display values for reference fields instead of the actual sys_id.

Q: How do you use the sysparm_exclude_reference_link parameter in REST API requests?
A:
The sysparm_exclude_reference_link parameter excludes the reference link in the response for reference fields, reducing the size of the response.

Q: What is the use of the sysparm_suppress_pagination_header parameter?
A:
This parameter suppresses the pagination-related headers in the response, which is useful when pagination information is not needed.

Q: Explain how to perform batch operations using the ServiceNow REST API.
A:
Batch operations are performed by sending multiple operations in a single HTTP request using the batch endpoint.

Q: What is the purpose of the sysparm_input_display_value parameter?
A:
The sysparm_input_display_value parameter allows the input data to be provided as display values instead of sys_ids.

Q: How do you retrieve related records using the REST API?
A:
Use the sysparm_include_related parameter to include related records in the response.

Q: What are Scripted REST API resources in ServiceNow?
A:
Scripted REST API resources are endpoints defined within a Scripted REST API that specify the HTTP methods and scripts for handling requests.

Q: Describe the purpose of the sysparm_query_no_domain parameter.
A:
The sysparm_query_no_domain parameter is used to ignore domain separation and retrieve records across all domains.

Q: How do you enable CORS for REST API requests in ServiceNow?
A:
Enable CORS by configuring the CORS rules in the System Web Services > REST API CORS Rules module to allow requests from specific origins.

Q: Explain the sysparm_view parameter in a REST API request.
A:
The sysparm_view parameter specifies the view in which the data should be returned, allowing for different layouts of the same data.

Q: What is the purpose of the Inbound REST API in ServiceNow?
A:
The Inbound REST API allows external systems to interact with ServiceNow resources by making HTTP requests to create, read, update, and delete records.

Q: How does Basic Authentication work in ServiceNow REST API?
A:
Basic Authentication involves sending the username and password encoded in Base64 in the HTTP header of the API request.

Q: What is OAuth 2.0, and how is it used in ServiceNow REST API?
A:
OAuth 2.0 is an authorization framework that allows applications to obtain limited access to user accounts without exposing user credentials. ServiceNow supports OAuth 2.0 for secure API access.

Q: What HTTP methods are supported by ServiceNow’s REST API?
A:
The REST API supports GET, POST, PUT, PATCH, and DELETE methods.

Q: How can you retrieve a specific record using the REST API in ServiceNow?
A:
Use the GET method with the specific record’s Sys ID in the URL endpoint.

Q: What is a REST message in ServiceNow?
A:
A REST message defines the HTTP method, endpoint, and authentication for a REST API call, configured in the REST Message module.

Q: How are query parameters used in REST API requests?
A:
Query parameters filter and refine the data returned by a REST API request by appending conditions to the URL.

Q: How is pagination handled in ServiceNow REST API responses?
A:
Pagination is managed using the sysparm_limit and sysparm_offset parameters to control the number of records returned and the starting point of the records.

Q: What is the difference between PUT and PATCH methods in the REST API?
A:
PUT updates a resource by replacing it with the request payload, while PATCH updates only specified fields of a resource.

Q: Describe how to create a new record using the REST API.
A:
Use the POST method with the appropriate endpoint and include the record data in the request body.

Q: How do you update an existing record using the REST API?
A:
Use the PUT or PATCH method with the record’s Sys ID in the URL endpoint and include the updated data in the request body.

Q: Explain the DELETE method in the context of ServiceNow’s REST API.
A:
The DELETE method removes a specific record from the ServiceNow database by specifying its Sys ID in the URL endpoint.

Q: What is the role of the sysparm_fields parameter in REST API requests?
A:
The sysparm_fields parameter specifies which fields should be returned in the response, reducing data transfer.

Q: How can you ensure secure communication between a client and the ServiceNow REST API?
A:
Secure communication is ensured by using HTTPS and implementing OAuth 2.0 or Mutual Authentication (mTLS).

Q: What are REST API Rate Limits in ServiceNow?
A:
Rate limits control the number of API requests a user can make within a specified time period to prevent abuse and ensure system stability.

Q: How do you configure a REST API rate limit in ServiceNow?
A:
Rate limits are configured in the System Web Services > REST API Rate Limits module by defining rules for different users or roles.

Q: Describe how errors are handled in REST API responses.
A:
Errors are indicated by HTTP status codes in the response, with specific error codes and messages provided by ServiceNow.

Q: What is the sysparm_query parameter used for in a GET request?
A:
The sysparm_query parameter filters records based on encoded query strings.

Q: Explain the concept of a Scripted REST API in ServiceNow.
A:
Scripted REST APIs allow developers to create custom REST endpoints and implement server-side scripts to define their behavior.

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