The Griffith's Valuation database is currently unreachable online at AskAboutIreland.ie – the most popular free site for Irish family historians to search this important collection.
How long this has been the case, I don't know, but I was notified of it yesterday lunchtime*.
The techies are dealing with it and hope to have the material back up and available soon.
* h/t to Dublin-based pro genealogist Claire Bradley.
UPDATE 17 October: The database is back online, which is good news. I'd like to say it's running fine, but it isn't for me. It's very very slow. Maybe that's because so many people are using it after its time offline... I don't know. It's just about usable, if you're feeling patient. Presumably it'll settle.