The email address of the domain name administrator is a little confusing
because you expect an @ symbol but none exists. In the example above,
root.ns.mydomainnameserver.com means
[email protected]. Replace this with the email
address for your admin, using a dot instead of the @ symbol. Remember the
dot at the end.
The serial number is a revision numbering system. It is changed every time
the file is changed. Convention is to use YYYYMMDDnn, where YYYY is year,
MM is month, DD is day, and nn is an extra number to allow you to increment
when multiple edits and saves occur in one day. For example, 2018080600
is the first edit on August 6, 2018.
The refresh rate sets the time, in seconds, when the slave DNS server will
refresh from the master DNS server.
The retry rate sets how long to wait after a failed refresh before making
another attempt.
The expiration sets how long to keep a zone file cached.
Minimum is the default time that slave servers should cache the zone file. If
your DNS record changes frequently, you want to set this to a low number,
like 12 hours or so. If infrequently, then every 1 to 5 days is a good balance
between keeping updated and keeping requests served quickly.
TXT
You can put any text you like in a TXT record. This record is most commonly
used to implement the Sender Policy Framework (SPF), which is an email
validation system designed to help detect and prevent email spam by
detecting email spoofing. With spoofing, email is sent out to look like it
originated in one location when it actually originated somewhere else. SPF
records must indicate the version identifier for SPF and a default mechanism.
Here is an example of SPF info in a TXT record:
Click here to view code image
example.com. TXT "v=spf1 -all"
This indicates to use SFP version 1 and that no servers at this domain send
email. If your server does not send email, use this to prevent email/web
hosting companies from blocking your domain if someone tries to send email
pretending to come from your domain.
If your server sends email, you use something like this: