I have a multi tenant application So, For example: We have a tenant Den.kansoftware.com and he need this application to work on his own domain i.e. www.Den.com
How this can be done.
You can write your own tenant resolver similar to https://github.com/aspnetboilerplate/aspnetboilerplate/blob/dev/src/Abp.AspNetCore/AspNetCore/MultiTenancy/DomainTenantResolveContributor.cs and determinethe current tenant according to your own logic.
Then, you need to add your custom resolver as the first item in tenant resolvers, see https://aspnetboilerplate.com/Pages/Documents/Multi-Tenancy#determining-current-tenant