Long CDS vs Short CDS

I am very confused with going Long CDS and going short CDS positions.

I have been doing some curriculum EOC questions and got incorrect answer. As I understand, protection buyers going Long on CDS position to transfer credit risk to protection seller, who going Short on CDS. However, the curriculum said something like this in its EOC solution: “shorting (buying protection) a long-term (20-year) CDX and going long (selling protection) a short-term (2-year) CDX”. Please correct my misunderstanding. I have spent hours on this.

Read my post https://www.analystforum.com/forums/cfa-forums/cfa-level-ii-forum/91364258