Completing a Challenge proves that you own the domain for which you are creating the certificate. There are two types of challenges :
HTTP - in the HTTP challenge, you will place an extensionless file with a specific token value content in a folder with a specific token name in the root of your website. To validate the website domain, a GET request is sent to the extenionless file in your website and the validator checks for the correct token value in the content.
DNS - in the DNS challenge, you will create a DNS TXT record with a specific token name as its name and a specific token value as the record’s value. The DNS TXT record is created in the Management Portal of your DNS provider (eg. GoDaddy, DNSimple, etc.). To validate the website domain, a DNS search is used to look for the DNS TXT record and the validator will check for the correct DNT TXT record value.
You will use the API to create a Challenge and in the API’s response the token name and token value will be returned. You can then use to token name and value to complete the challenge using the HTTP or DNS method.
After you have completed the Challenge, you can then proceed to create the Certificate using the CertificateOrder object that is returned in the response.