On-line degrees are beginning to be quite common. Most colleges in North Dakota and the surrounding area offer degrees on-line. In order to get a qualify education, it works much like any education. You get as much out as you put in (usually). The key is the accreditation of school. All state-funded schools are accredited. This means a body of professionals in specific fields review the curriculum (about every 5 years) to determine if the correct material is being taught to students. There are a number of accrediting institutions, but North Dakota colleges are accredited by North Central. In some schools particular programs have additional accreditation standards determined by law or professional organizations. Some of these professions would incude medical doctors, registered nurses, dental hygienists, automotive mechanics, etc.)
Private schools are usually reviewed by smaller accrediting bodies.
Charlotte Jones sent me a link to an article about accreditation which you may find interesting. http://www.accreditedonlinecolleges.net/