One issue that has been the topic of some pointless discussion iswhether a mail server should have an A record or an MX record.
It's harmless not to have an MX record that points to yourself,but having one can save people a DNS query in many situations.
Answers to DNS queries have three sections: answer records, authorityrecords, and additional records. Authority records are the NS records ofthe authoritative nameservers (and SOA records for negative
With the growth of XHTML, some HTML documents have started sproutingthings of the form ' ' or ' ', intended to representempty tags. Sometimes this is due to attempts at XHTML to HTMLcompatibility , andsometimes it's just due to HTML superstitions. (Most people who writeHTML are not experts and have not read the W3C specifications , so superstitions arenot uncommon.)
These people and documents are making a mistake. Unfortunately, thereare three entirely