Terje, I looked into this a while back but I didn't actually look closely at the traffic content. I don't think this is mis-categorised, sophos admit they use port 53 for their updates but don't mention that they actually tunnel it in DNS requests so I presumed the traffic was going directly between our clients and sophos until I noticed the flows were coming from our DNS server this morning. I think I need to do some more digging because from what I can see each session transfers around 600kB, so if that means the actual signature updates are passed through the DNS servers, it may be a good reason to move away from sophos. If they just check to see if they need updates that way, it would be less of an issue, but 600kB seems a lot just for that. Thanks,
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