Thanks all!
I just make a test for other category of domain.
We are focusing on three category : keyword domain, brandable domain, and numeric domain (value of numeric domain is rising up day by day, but I'm not see it can be developed).
Besides three categories above, hacked domain also received a lot of attention, but its value is usually bad luck.
According on Namebio, I see a lot of name with 'dot' prefix, so I make a test. Begin with the phrase 'dotcom', because it's the umbrella of dot world
.
The dotcom.com was created 1994, currently own by NetworkSolution, a big company, so I think the dotcom.com is worth.
Next step I check the dotcom.net, it's was created 1996, own by an individual, parking at Sedo, and if not have 10k, I can't make an offer for this domain. Very confused, very suspiciously, so I posted here to consult your opinion.
Thank you once again.