DIYbanter - View Single Post - Sink Drain

wrote:
I just installed a sink drain.

The drain has two retangular holes (about 1" by 1") in it just below
the top surface
of the sink and above the underside surface of the sink (above the
undersink gasket)

What are the purpose of these holes? Seems like they just provide a
cavity between
the outersurface of the drain and the inner surface of the hole in the
sink where the
drain fits. Drain water must accumulate in this cavity, I would think?

I'm not familiar with a vent under the sink. Usually the air is taken
in at the sink overflow which is on the inside surface of the sink near
the top as MasterBlaster posted, but I'm pretty sure that's what you're
looking at - vent holes.

R