Cannot ping a single website when I am logged into my account
Check if you have an entry for sample.com in /etc/hosts. 

Entries in /etc/hosts take precedence over DNS. In your case, DNS is properly configured (nslookup returns the correct IP), but ping will use the information in /etc/hosts instead. This is also true for any CLI command like curl or wget and most apps (some apps don't appear to honor /etc/hosts.)

Note that the host name specified in the command must match an entry in /etc/hosts exactly, for example:

192.168.16.3   myserver.mydomain.com


will direct ping myserver.mydomain.com to try to reach 192.168.16.3, but ping myserver will query DNS with whatever default domain is configured in /etc/resolv.conf.

For more information on /etc/hosts, see man hosts and this Wikipedia article on /etc/hosts. For more information on /etc/resolv.conf, see this Wikipedia article on resolv.conf.