Unexpected errors may appear when using hostnames without a DNS domain

[TheWitness]

Describe the bug

If you are using a hostname and not a Fully Qualified Domain Name for one of your Cacti data collections, when you save the data collection the dns_get_record() exception is thrown.

To Reproduce

See the note above.

Expected behavior

Cacti should not throw these errors.

[netniV]

We should see if we use the function elsewhere and update as appropriate

[TheWitness]

I remember the settings plugin has a DNS resolver, but if memory serves me right, it's using RAW socket communication, which likely won't work with secure DNS. We should convert that function/library.

[TheWitness]

@cigamit Should comment.