I can confirm sdf.org doesn't exist using Firefox but shows ok with Chromium.
On my debian pc. Probably a firefox bug? Oh, wait.. The second time I tried sdf.org it showed up correctly, so I'm guessing it's a temporary DNS name resolution where it fails on the first attempt.. Doesn't make sense!
On my debian pc. Probably a firefox bug? Oh, wait.. The second time I tried sdf.org it showed up correctly, so I'm guessing it's a temporary DNS name resolution where it fails on the first attempt.. Doesn't make sense!