Hi,
I wonder why port 53 would fail when my ufw status shows:
53 ALLOW Anywhere
53/udp ALLOW Anywhere
53 (v6) ALLOW Anywhere (v6)
53/udp (v6) ALLOW Anywhere (v6)
www.example.com:
DNS isn’t configured properly for this domain:
DNS resolution failed
(A: All nameservers failed to answer the query www.example.com.
IN A:
Server 200.00.00.1 UDP port 53 answered SERVFAIL;
Server 300.00.00.1 UDP port 53 answered SERVFAIL;
Server 300.00.00.1 UDP port 53 answered SERVFAIL;
Server 400.00.00.1 UDP port 53 answered SERVFAIL;
Server 500.00.00.1 UDP port 53 answered SERVFAIL;
I entered nmap scan “my IP address” and got:
Nmap scan report for mail.example.com (my IP address)
Host is up (0.000015s latency).
Not shown: 994 closed ports
PORT STATE SERVICE
22/tcp open ssh
53/tcp open domain
80/tcp open http
443/tcp open https
993/tcp open imaps
995/tcp open pop3s
Nmap done: 1 IP address (1 host up) scanned in 1.80 seconds