“mozilla/5.0 (windows nt” “opera/9.80 (windows nt” is part of a user agent string that you may see in your access logs. Part of that string (it is not complete) is listed in the Most Common User Agents
It is possible that this user agent string is a bot – it seem to refer to Windows XP and very frequently Windows XP useragents, especially IE6, are bots.
Here are two very common BOT useragents that are similar to the
"mozilla/5.0 (windows nt" "opera/9.80 (windows nt" string:
Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1; MRA 5.8 (build 4157); .NET CLR 2.0.50727; AskTbPTV/220.127.116.1190)
Opera/9.80 (Windows NT 5.1; U; en) Presto/2.10.289 Version/12.01
If you have a browser that has a console (like google chrome) you can type
navigator.userAgent to see what your browser’s useragent is: