III. Reserve Your Domain

How do you verify the availability of a domain?
All of the names that interest me have already been reserved, what to do?
Precautions when reserving a gTLD (.COM, .NET, .ORG) domain
Precautions when reserving a ccTLD (final .BR) domain
Is it possible to have a .COM.BR without a taxpayer ID number [CNPJ]?
I'm already registered with Registro.br, is this good or bad?
Careful with the subdomain
I discovered that my current domain is not good. What should I do?