The ISP industry is watching with interest the ongoing competition to operate the .net domain, which is a critical component of the Internet's infrastructure.

Five domain name registries submitted bids on Jan. 19 to the Internet Corporation for Assigned Names and Numbers (ICANN) to run the .net registry. A winner will be selected in March.

The .net registry operates the highly available and redundant servers around the globe that handle four billion .net queries on average per day. The .net registry also supports a massive database that includes information about each .net name and handles additions, deletions and changes to that information.

VeriSign and its predecessor Network Solutions have operated the .net registry since 1993. VeriSign is competing against several other domain name registries including Afilias, Core++, Sentan Registry Services and DENIC to keep its .net business.

Five million .net names have been registered, compared to 30 million .com names. Although it is less popular than .com, the .net domain is just as important to ISPs as the Internet's main e-commerce domain.

Many ISPs including Earthlink and Comcast run their e-mail operations on the .net domain. VeriSign estimates that 155 billion e-mails are sent each day either directly or indirectly via .net.

VeriSign, which operates both the .net and .com registries, says .net is the largest top-level domain when ranked by the number of hosts connected to the Internet. The .net domain represents 58% of worldwide hosts and 30% of the world's name servers, VeriSign says.

That's why some ISPs are already involved in the competition:

* The Core++ bid includes as a partner Telefonica Group, a leading ISP in Latin America. Other members of the Core++ team include the South African operators of the .za domain, the Korean agency that operates the .kr domain and the Internet Software Consortium.

* DENIC's members include Deutsche Telekom, AT&T Germany, Cable & Wireless and Melbourne IT. Based in Frankfurt, Germany, DENIC is a non-profit organization that operates the .de domain, which is the Internet's second largest domain. 

* Sentan Registry Services is a joint venture between NeuLevel, which operates the .biz and .us domains, and Japan Registry Services, which operates the .jp domain. NeuLevel, in turn, is a joint venture between telephone database operator NeuStar and Australian ISP Melbourne IT.