To get wildcard supported certificates, we need to pass the challenge which requires adding TXT records in your dns records.
To get certificates for single domains, there is no need to modify dns records. Check this link https://micropyramid.com/blog/configure-ssl-with-letsencrypt-and-nginx/ for more info.

In any business communication among employees, customers, users and clients are very important. To collaborate and communicate in Salesforce we use communities. Communities will make sure that the customers get solutions to their queries in one place.

Apex provides collections such as List, Set, Map. These are similar to arrays, but these collections have advanced features and easier methods than an array. Set is a collection of unordered elements and don't contain any duplicate values.

Salesforce is used by many users whose native languages are different, If the application doesn't have any Multilanguage feature, it would be difficult for the users to use it. So, in Salesforce we have Custom Labels where multilanguage applications can be created.

In any Organization, Support is important to enhance good relationship with their customers. In Salesforce, whenever a customer mails any need of support or interaction with the organization, then the mail is automatically converted into case and assigned to the certain user based on the subject and information available in that mail. In this, we will look into Email-to-Case and On-Demand Email-to-Case.

In salesforce organization, when you have to work on lot of leads and each lead will be at different stage. To make it easier to manage all those leads you should automate your business process, you can do it by creating reminders such that you won't miss anything on anyone.

Customers have their own organizations in a shared platform. Sometimes, one organization may require to fetch data from the other one. To share data between two organizations, there are some methods in salesforce, one of them is establishing Salesforce to Salesforce connection in both organizations.

Apex provides collections such as List, Set, Map. These are similar to arrays, but these collections have advanced features and easier methods than an array. We will see about List, which is used widely in salesforce.

In the salesforce organization, when you are building a component or application, it's important to know how the component or application should be distributed to other organizations or customers. So for this, we have packages in salesforce in which developed components and applications can be combined and distributed to other salesforce organizations. In this, we have defined different types of packages and their usage.

As we know there will be role hierarchy in many organizations and permissions are assigned according to their roles. So, When a record or data is updated or inserted then automatically it should be approved by some assigned user. To do this In salesforce, we use Approval process method to automate the functionality.