IP address?...
BINGO - that’s what I was trying to remember. Google search turned up this:
IP addresses 11.11.18.0 to 11.11.18.255
11.11.18.0 - 11.11.18.255 is an IP address range owned by DoD Network Information Center and located in United States - select an address below for more geolocation details
However 11.11.18 is evidently NOT an IP address and was a recent date.