I run a Domain Name Registration company. So you can understand how important domain names are for me. I have to change the Nameservers of my client domains numerous number of times sometimes in a day. But I am facing a typical problem in my business due to my ISP. It takes a lot of time for them to update their Name servers and many a time a site propogates after days and nameserver changes also reflect after a lot of time. So I thought to overcome this I should install a local name server in my system. The Name server should be such that I can edit the values of cached dns. In this way the changes will be reflected then and there and I will overcome my problem. But now the question is: does such type of nameserver exists? If yes, please recommend the best one. Does any other way exists to overcome my problem?