What is the purpose of a PTR record?

Performing a DNS lookup with dig results in this answer:

What might be wrong in the zone definition?

What directive can be used in named.conf to restrict zone transfers to the 192.168.1.0/24
network?

To securely use dynamic DNS updates, the use of TSIG is recommended. Which TWO
statements about TSIG are true?

Which option is used to configure pppd to use up to two DNS server addresses provided by the
remote server?

A DNS server has the IP address 192.168.0.1. Which TWO of the following need to be done on a
client machine to use this DNS server?

The mailserver is currently called fred, while the primary MX record points to
mailhost.example.org.
What must be done to direct example.org email towards fred?

Which of these ways can be used to only allow access to a DNS server from specified
networks/hosts?

There is a restricted area in an Apache site, which requires users to authenticate against the file
/srv/ www/security/site-passwd.
Which command is used to CHANGE the password of existing users, without losing data, when
Basic authentication is being used.

Consider the following
<code>
/srv/www/default/html/restricted/.htaccess
AuthType Basic
AuthUserFile / srv/www/ security/ site-passwd
AuthName Restricted
Require valid-user
Order deny,allow
Deny from all
Allow from 10.1.2.0/24
Satisfy any
</code>
Considering that DocumentRoot is set to /srv/www/default/html, which TWO of the following
sentences are true?