lets encrypt - Letsencrypt how to use --preferred-challenges -

this command:

$ letsencrypt certonly --manual --preferred-challenges dns --email foo@bar.com --domains test001.bar.com 

outputs:

letsencrypt: error: unrecognized arguments: --preferred-challenges dns 

from documentation here: https://certbot.eff.org/docs/using.html#certbot-command-line-options

i find:

  --preferred-challenges pref_challs                         sorted, comma delimited list of preferred                         challenge use during authorization                         preferred challenge listed first (eg, "dns" or "tls-                         sni-01,http,dns"). not plugins support                         challenges. see                         https://certbot.eff.org/docs/using.html#plugins                         details. acme challenges versioned, if                         pick "http" rather "http-01", certbot select                         latest version automatically. (default: []) 

why error?

found answer, although website states letsencrypt , certbot same. seems not case.

$ apt-get install letsencrypt $ apt-get install python-pip $ pip install --upgrade pip $ pip install certbot $ certbot certonly --manual --preferred-challenges dns --email foo@bar.com --domains test001.bar.com 

does trick