loose name checking

loose name checking: A form of domain name checking DNS uses that examines characters in DNS names for valid American National Standards Institute (ANSI) character compliance. However, loose name checking does not check for compliance with DNS naming requirements and valid character usage for Internet host names, as specified in RFC 1123, Requirements for Internet Hosts - Applications and Support.

For RFC compliance, DNS domain names will use name labels made up only of valid uppercase and lowercase letters, number characters, and hyphens (A through Z, a through z, 0 through 9, and -) separated by periods.