subdomain

(redirected from Third-level domain)
Also found in: Acronyms.

subdomain

A lower-level component of a domain name. For example, www.mycompany.com and support.mycompany.com are subdomains of mycompany.com, which is known as a "second level domain." See naked domain, zone and root domain.
References in periodicals archive ?
In February the new registry of the .CO name space, .CO Internet S.A.S, had liberalized the allocation of the Colombian third-level domains and initiated the registration of second-level domains.
Because only third-level domains were previously available, john.smith.name and fred.smith.name could be registered to users on two separate ISPs, GNR owned smith.name and had to act as a central relay for email.
Recently, RegistryPro petitioned the Internet Corp for Assigned Names and Number to allow it to change the terms of the contract it is negotiating to allow it to offer second-level names like johnsmith.pro, saying the market fro third-level domains was dubious.

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