In this vein there's also 3 TEST-NETs, all /24 but still useful. I've been known to use TEST-NET 1 for Wireguard: 192.0.2.0/24. The other two are 198.51.100.0/24 and 203.0.113.0/24.
There's also 198.18.0.0/15, Wikipedia says it's "Used for benchmark testing of inter-network communications between two separate subnets"[1]. Use this if you really want to thumb your nose at the RFC police.
I love how google likes to completely ignore what I'm trying to search for. I wish I could think of an example because it happens to me often, but I can't so I'll make one up.
Imagine you're searching for tail lights for your car or something, but you don't know the size, so you search "Astra tail light size". This might bring up headlights. Wrong but no matter, you'd go on to google "Astra tail light size -headlight -head" or something.
What Google seems to have been doing to me recently is ignoring those negated terms, ignoring quotes, and just giving me the same results again and again. It's really getting annoying. Google seems to assume it knows what I'm looking for, and that my search query is just completely wrong and not what I want.
Note that the car stuff is just an example, I'd expect Google to not give you headlights the second time. It generally but not exclusively happens to me when searching things that are more technical. ESPECIALLY when it's a consumer level thing I'm trying to get info on, Google likes to assume it's giving you errors and you're trying to fix it. Which makes sense for most users, but god it's frustrating when every combination of advanced search parameters you try does nothing!
Google search needs a checkbox or something to turn off it's cleverness and just do an actual search.
There's also 198.18.0.0/15, Wikipedia says it's "Used for benchmark testing of inter-network communications between two separate subnets"[1]. Use this if you really want to thumb your nose at the RFC police.
[1] https://en.wikipedia.org/wiki/List_of_reserved_IP_addresses