ruby on rails - Not able to install jekyll without root access -

i trying install jekyll, there documentation says install :

gem install jekyll 

when try above gives error:

error: not find valid gem 'jekyll' (>= 0), here why: unable download data https://rubygems.org/ - no such name (https://api.rubygems.org/specs.4.8.gz)

but when tried:

sudo gem install jekyll 

it worked fine , gave following output :

successfully installed jekyll-2.5.3

1 gem installed

i went through this write permission, while problem facing not being able access source.

my internet connection fine , https_proxy unset not behind proxy server. sudo/root access doing able access when can't?