Website is not working due to DNS issue

Created:

2016-11-16 13:15:37 UTC

Modified:

2017-06-03 12:28:30 UTC

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Website is not working due to DNS issue

Applicable to:

  • Plesk 12.5 for Linux
  • Plesk 12.0 for Windows
  • Plesk 12.0 for Linux

Symptoms

Sites are not loading due to DNS issue.DNS TCP port is opened.

# nmap -p53 203.0.113.2
Nmap scan report for 203.0.113.2
Host is up (0.40s latency).
PORT STATE SERVICE
53/tcp open domain

Cause

DNS UDP port is not opened. This can be verified using nmap utility.

# nmap -sU -p53 203.0.113.2
Nmap scan report for 203.0.113.2
Host is up (0.24s latency).
PORT STATE SERVICE
53/udp open|filtered domain

Resolution

Open 53 UDP port on the server firewall.

# iptables -I INPUT -m tcp -p tcp --sport 53 -j ACCEPT
# iptables -I INPUT -m udp -p udp --sport 53 -j ACCEPT
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