Configure MX Record

A mail exchanger record (MX record) is a type of resource record in the Domain Name System that specifies a mail server responsible for accepting email messages on behalf of a recipient's domain, and a preference value used to prioritize mail delivery if multiple mail servers are available.

Edit MX Record in /var/named/zmailtech.com.zone file. for zmailtech.com domain.

[root@master ~]# vim /var/named/zmailtech.com.zone
[root@master ~]# cat /var/named/zmailtech.com.zone
$TTL 1D
@       IN SOA  ns1.zmailtech.com. admin.zmailtech.com. (
                                        2017121501      ; serial
                                        1D      ; refresh
                                        1H      ; retry
                                        1W      ; expire
                                        3H )    ; minimum
        IN      NS      ns1.zmailtech.com.
ns1     IN      A       192.168.10.2
master  IN      A       192.168.10.2
mail    IN      A       192.168.10.2

;CNAME Record
www     IN      CNAME   master.zmailtech.com.
ftp     IN      CNAME   master.zmailtech.com.
smtp    IN      CNAME   mail.zmailtech.com.

;MX Record
zmailtech.com.  IN      MX      10      mail.zmailtech.com.
zmailtech.com.  IN      MX      20      smtp.zmailtech.com.
[root@master ~]#

Check MX Record with dig command.


[root@master ~]# dig mx zmailtech.com

; <<>> DiG 9.9.4-RedHat-9.9.4-50.el7 <<>> mx zmailtech.com
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 41221
;; flags: qr aa rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 1, ADDITIONAL: 3

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;zmailtech.com.                 IN      MX

;; ANSWER SECTION:
zmailtech.com.          86400   IN      MX      20 smtp.zmailtech.com.
zmailtech.com.          86400   IN      MX      10 mail.zmailtech.com.

;; AUTHORITY SECTION:
zmailtech.com.          86400   IN      NS      ns1.zmailtech.com.

;; ADDITIONAL SECTION:
mail.zmailtech.com.     86400   IN      A       192.168.10.2
ns1.zmailtech.com.      86400   IN      A       192.168.10.2

;; Query time: 0 msec
;; SERVER: 192.168.10.2#53(192.168.10.2)
;; WHEN: Thu Dec 14 13:46:49 IST 2017
;; MSG SIZE  rcvd: 134

[root@master ~]#

Check zmailtech.com mx record with host command

[root@master ~]# host -t mx zmailtech.com
zmailtech.com mail is handled by 20 smtp.zmailtech.com.
zmailtech.com mail is handled by 10 mail.zmailtech.com.
[root@master ~]#