The top five generic top level domains (gTLDs) are .com, .net, .org, .info and .biz The “dot biz” top level domain is managed by Neustar. Based on information from Webhosting.info the .biz TLD has the fewest number of registered hosts - slightly more than 1 million of the 5 most popular gTLDs. As of early June 2005 there were about 76.9M domain names registered in total. The .biz domain represents about 1.5% of all registered domain names.
BIZ 1,172,013
Based on Exhibit F of Neustar’s Registrar Agreement, Neustar collects $5.30 per .biz registration per year, which means that their .biz business generates about $6.2M per year.
Neustar also manages the .us, kids.us, .cn (China) and .tw (Taiwan) domains. For the .us domain Neustar charges $5.50 per year according to Exhibit F of the usTLD ADMINISTRATOR-REGISTRAR AGREEMENT. There are 315,215 dot us domains according to DaomainWroldwide, which means that the dot us business is about a $1.73M per year business.
Based on a recent Verisign report, China has approximately 504,876 domain names. This could represent another $2.5M in business.
The most complete source of registered domain names is found at DomainWorldwide but I must note that the numbers here vary significantly from other numbers I found and for the most part they appear to be understated.
For .tw the count is:
com.tw: 93,480
idv.tw: 18,221
edu.tw: 4,048
net.tw: 3,768
total .tw: 107,973
Again, this could result in ~$0.5M per year in revenue.
So, how big is Neustar’s the domain name business based on this data? Lets total it up:
.biz: $6.2M
.us: $1.73M
.cn: $2.5M
.tw: $0.5M
Total: $10.93M
So, there is $130M for US number portability, about $7M for Number administration and pooling, and $10.93M for domain names. My guess is that there is about another $7M for number portability in Canada. So, that totals to about $154M, which leaves about $11M for “other businesses” based on these calcuations from publicly available data.