It's not just custom DNS setups.
a spokesman told us the flaw only affected those users with custom DNS setups on their personal networks
No, it affects EVERYONE. And if, like me, you're using a non BT router, you're using a non BT DNS server, and so they get zillions of hits, not BT.
The flaw only APPEARS to affect users who have got custom DNS setups, because we're the only people who notice our DNS being hit by multiple requests to Microsoft.
That's what really pissed me off about this issue. It was the suggestion that because the software didn't cause most people to complain (because they weren't aware of it), then it doesn't matter that you're making over half a million DNS requests a day to someone else's name server.
The question I've never managed to get answered is - why do they need to do this? These discs are basically clever access points. They are not routers, and they shouldn't care two hoots whether the internet is working or not. That's the job of the router.
Oh - and according to BT, the reason they do this is so that they can put a little red light on to alert the user that something has gone wrong if the internet goes down. As if the router doesn't already do this.
Anyway, we're promised a new firmware on June 21st, which is going to reduce the impact to once a minute, not once a second. Still more than is necessary though.