[SOLVED] swtching diode blocking dc

hi,
can switching diode block dc. if so how can it?

yes. It can. All diode would block DC in reverse bias till it's breakdown voltage.

Letting current pass in one direction and blocking it in the other direction is the most fundamental property of any diode. If you need an explanation of how a diode works in a particular circuit, post a diagram or a description.

The function of a Diode is to let pass the current in one direction (from Anode to Cathode). This basic function is known as rectification from AC to DC at a normal frequency (just to understand say 50, 100 Hz). Rest all the names are after their usage.
If we say a Switching Diode, we mean to say that the Diode is capable of with standing on High Frequency as a DC Blocker or as as a Rectifier. The normal or slow working diodes can not rectify the High Frequency and (normally) go short circuited.
Why this happens?
As the diode junction is not capable of getting it ready to to deal the Pulse after Pulse and this ability is known as REVERSE RECOVERY TIME, as is the SHORT REVERSE RECOVERY TIME as is the diode good for High Frequency use.
In the datasheet it is shown as Trr or Tr as obvious from the attached table:

There are many other uses of the Diodes hence different names, too.