I am talking about vespa crabro, the European hornet. All social wasps use pheromones to mark intruders. If you are being stung while close to a nest, yes, do walk away. That being said, I have been stung once (own mistake) while standing 2 meters away from a nest and nothing happened.

Curious. The reason I mentioned nests being close together upthread is because - per my understanding - both being stung by a wasp/hornet and killing one releases pheromones that makes other wasps/hornets go into aggressive mode. So I'm imagining the two nests being so close to each other will, eventually, trigger a war, which only ends once one of the side is eradicated. I wouldn't want to see anything like that near my house.