Ambethia::ReCaptcha::ReCaptchaError: getaddrinfo: hostname nor servname provided, or not known

Hi,

I have installed reCAPTCHA plug-in and I received about 7 errors on Hoptoad with following error message during the last 2 weeks:

Ambethia::ReCaptcha::ReCaptchaError: getaddrinfo: hostname nor servname provided, or not known

Stacktrace:

vendor/plugins/recaptcha/lib/recaptcha.rb:72:in `verify_recaptcha'
app/controllers/blog_controller.rb:30:in `new_comment'

skipped

I have tested access to http://api-verify.recaptcha.net from my VDS server. It has access to that URL and I don't understand why some users generate this mistake, but I (for example) don't have errors.

May be someone has any idea?

Thanks