Insert domain into the database.

This endpoint technically suggest a domain to the server.

It is required to have at least one valid DNS record for the domain to insert (eg.: A or AAAA). The domain is sent to an underlying channel, so returns fast, but the client will not get informed about the result. If the underlying channel is full, hangs until there is free space to send.

This endpoint uses blacklist and rate limiter to prevent garbage and resource exhaustion (eg.: sending invalid domain results a block for some time).