VAC ratings & VDC ratings from components
TL;DR; If it doesn't mention a DC rating, then it's not been tested nor rated for switching DC. You shouldn't use the switch for DC (unless the manufacturer tells you otherwise).

Switching DC is a lot harder to do than for AC (especially at higher voltages/current), becuase of arcing.
When you switch AC, even if you interrupt it at the peak voltage, it will be at most 1/4 cycle before the voltage drops to zero, and self extinguishes (is that the right word?) any arc that may have formed between the contacts.
When you switch DC, there supply voltage is constant, which means any arcing will continue until conditions cease to be favourable, and may even prevent the switch from openning at all (welds shut). The stop point is either the gap between the contacts gets large enough (depends on voltage, humidity, etc.), or the contacts become sufficiently corroded and caked in carbon to provide enough resistance to stop the arc (which in turn reduces the operating life of the switch).
DC rated switches will have extra mechanisms to help overcome this risk of arcing - such as fast acting contacts (e.g. spring loaded) to open a gap as quickly as possible, and prevent the contacts from welding together.

If you know you aren't going to be changing the switch when there is a large DC current flowing (e.g. its a DPDT switch that you toggle before turning anything on), then you can relatively safely use switch for DC at the AC rated voltage.
However, if you are using it to interrupt a current, the AC current rating can not be used to infer any characteristics about DC operation, other than the safe DC current will be significantly lower.