Ask a DNS question. Thank you for configuring sendmail...

Ask a DNS question. Thank you for configuring sendmail... -- Linux Enterprise Application-Linux server application information. For details, refer to the following section. Hello everyone, I encountered a Problem When configuring sendmail. My DNS can now be resolved normally and can work normally through nslookup testing. Now I want to configure a sendmail server, but there is a problem in the following host-t mx yangqiang.edu.cn test. The result is: Host yangqiang.edu.cn not found: 3 (NXDOMAIN ), I think the MX configuration in the dns is incorrect, but I checked it several times and did not find any problems. Please help me and give me some advice. The following is my configuration file:
The following describes the content of named. conf:
Zone "yangqiang.edu.cn" IN {
Type master;
File "yangqiang.edu.cn. zone ";
Allow-update {none ;};
};
Zone "1.168.192.in-addr. arpa" IN {
Type master;
File "192.168.1.zone ";
Allow-update {none ;};
};

The following describes the related content of 'angqiang .edu.cn. Block:
$ TTL 86400
@ In soa yangqiang.edu.cn. root.yangqiang.edu.cn .(
42; serial (d. adams)
3 H; refresh
15 M; retry
1 W; expiry
1D); minimum
In ns dns.yangqiang.edu.cn.
@ In mx 10 mail.yangqiang.edu.cn. // here I have configured the MX record.
Dns in a 192.168.1.254
Mail in a 192.168.1.240
Www in a 192.168.1.241
Press in a 192.168.1.242
Pt in a 192.168.1.243
Vod in a 192.168.1.244

Please take a look. Thank you ..