[说明]
下面是某学校一台Linux服务器下域名服务主配置文件/etc/named.conf的内容：
options {
directory "/var/named";
};
zone "." IN {
type hint;
file "named.ca";
};
zone "0.0.127.in-addr.arpa" IN {
type ;
file "named.local";
};
zone " net.edu.cn " IN {
type slave;
file "named.hosts";
s{202.122.58.101}
};
zone "58.112.202.in-addr.arpa " IN {
type slave;
file "named.hosts";
s{202.122.58.101}
}; 服务器类型包括______、______、______。该服务器类型为______，如果要增加一条主机(A)类型的资源记录，则需要在______上完成。