Channel is not Active?

[cletsimon]

sudo pear channel-discover pear.domain51.com
Discovering channel pear.domain51.com over http:// failed with message: channel-add: Cannot open "http://pear.domain51.com/channel.xml" (Connection to `pear.domain51.com:80' failed: php_network_getaddresses: getaddrinfo failed: nodename nor servname provided, or not known)
Trying to discover channel pear.domain51.com over https:// instead
Discovery of channel "pear.domain51.com" failed (channel-add: Cannot open "https://pear.domain51.com/channel.xml" (Connection to `pear.domain51.com:443' failed: php_network_getaddresses: getaddrinfo failed: nodename nor servname provided, or not known))