[ashleyn]

My thoughts exactly:

"The network management software interpreted the empty field as a 'wildcard,' meaning that the software understood the blank field as an instruction to block all calls, instead of as a null entry. This caused the switch to block calls from every number in Level 3’s non-native telephone number database."

WTF kind of crappy design is that?

[cesarb]

Probably a filtering interface with several fields, in which you fill the ones you want to filter on. If you don't fill a field, it's not used as a criteria for filtering (so empty fields are a "don't care" for that field's criteria).

[greglindahl]

This is the basic design pattern: "Google mistakes entire web for malware"

https://www.theregister.co.uk/2009/01/31/google_malware_snaf...