When someone is in DND mode in their instant messanger program, it means "DO NOT FUCKING DISTURB" because that person may just have fucked up 756 domains and they might be a bit busy triping balls trying to fix it. So you should just STFU and leave them alone till they get off DND mode, it's quite a simple procedure to grasp.

This has been Netiquette lesson from your pal, - Grimm