Why Does NATO have to Guess?

Several articles have come out this week about NATOs websites being interrupted while it gets together to talk about Russian aggression in the east.  Ones like http://www.wsj.com/articles/nato-linked-websites-go-down-cyberattack-suspected-1468001918  describe the wonder by NATO officials about whether or not a cyber attack has taken down those sites.  It says a lot about NATO that they have to speculate about whether they have been attacked.

This may be politics talking and not real Information Technology, because almost everywhere I ever worked, we would know if we were brought down by hackers and would not have to speculate very long about it.  Alarm bells would be going off on our systems and administrators would be looking at the traffic patterns to determine if we were suddenly overcome with a gigantic interest in NATO affairs, or a groups of hackers were running a DDOS attack from somewhere.  If the NATO administrators are so uninformed about their own systems, then there is something wrong with them.