The last part is the top level country code.
The one before is a SUB domain or second level domain code.
In your case, the .ch. must refers specificaly to one of the four islands of that country.
In the United States, you have the same where .ca.us refers to California, while .ca by itself refers to Canada.
.on.ca is for the Canadian province of Ontario and .qc.ca is for the province of Québec.
Electro
June 2015