This version of Ubuntu, code-named "Natty Narwhal", was released on Apr 28, 2011 and reached End-of-Life Oct 28, 2012. Questions about unsupported versions are likely to be closed as off-topic.

Code name: Natty Narwhal

Ubuntu Flavors available under 11.04 (questions on all are allowed):

The 11.04 Ubuntu variants - Mythbuntu, Ubuntu Studio, Xubuntu and Lubuntu - are not commercially supported by Canonical.

Ubuntu Editions available under 11.04 (questions on all are allowed):

Ubuntu 11.04 reached its end-of-life on October 28, 2012.

Questions on are considered off-topic since it had reached the end of life.

Ubuntu releases