Can't add domain contain underscore like : sub_example.domain.com

Hi I can’t add domain with sub_example.domain.com why ? I tested it from another panel or dns provider like cloudflare, there is no such error. can you help with this ?

Hi @maryam,

Underscore is not allowed to be used in labels for hostnames. It is allowed for domain names but in this case you are adding a hostname.

  • domain name is the identifier of a resource in a DNS database
  • label is the part of a domain name in between dots
  • hostname is a special type of domain name which identifies Internet hosts

So, don’t use underscore if you are adding a hostname.

Edit: Also, you won’t be able to create a certificate if your hostname contains underscore:

This is what was voted by CAB Foum:

After April 30, 2019, underscore characters (“_”) MUST NOT be present in dNSName entries.

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