When was that? I don't recall any episodes where the Defiant landed.
Logically it would make sense that the ship could land, but I don't believe it ever did so on screen.
There are none.
There are landing struts on the MDS, the Defiant is already a problematic ship with the mysterious "deck 5" that according to the MSD does not exist, size inconsistencies and the Lazarus effect (AKA reusing old footage when the ship was destroyed and the new one had a different registry number).
The real answer is the producers did not knew it had landing struts and since we never seen a White Star landing on B5 ...
The Nova Class actually could land. The tech's show landing struts in the underside of the 2ndary hull. Actually the Defiant could ALSO land on a planets surface and be used as a base in the original blue prints. Only b/c of production cost is why we never saw it.
But this lends the question again.. where would you land? There really is no point in doing so in this game.
EDIT: my bad f2pdrakron, i should have read all the post before i said anything... i basically repeated just what you said..