I would better say "cold contacts".

I started networking 5 years ago and even today, I can say: everybody is up-to-date or most part of my contatcs for sure.
It´s very important to keep your contacts "warm", especially those people you did´t see or contacted for a long time.

Short initial email or call do wonder. I think just about my business partners or colleagues in U.S., simple email with "how is everything..." is enough to bring you back in mind.

Keep your contacts busy or you gonna be a "cold contact" after a while.