The IRS National Office determined that the proper life for amortization of an acquired domain name is 15 years in Chief Counsel Advice 201543014.  That was true whether the domain name was a generic domain name (one that doesn’t refer to a specific company or product name, say “dogfood.com”) or a non-generic domain name (one that is associated with a specific company, product or service name, such as “microsoft.com”).