Configuring OpenDNS

A good DNS service is extremely important. Asterisk can performs a lots of DNS requests and it can lock awaiting for an answer. It is strongly suggested to configure OpenDNS servers:

nameserver 208.67.222.222
nameserver 208.67.220.220
nameserver 208.67.222.220
nameserver 208.67.220.222

If your DNS configuration is managed by NetworkManager, edit your /etc/sysconfig/network-scripts/ifcfg...

DNS1=208.67.222.222
DNS2=208.67.220.220
DNS3=208.67.222.220
DNS4=208.67.220.222

If you are using CentOS 9 and derivative distributions, edit your /etc/NetworkManager/system-connections/...nmconnection

dns=208.67.222.222;208.67.220.220;208.67.222.220;208.67.220.222;

OpenDNS is currently being blocking some countries, like France:

dig @208.67.222.222 www.mirtapbx.com +norecurse +comments

; <<>> DiG 9.11.4-P2-RedHat-9.11.4-26.P2.el7_9.16 <<>> @208.67.222.222 www.mirtapbx.com +norecurse +comments
; (1 server found)
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: REFUSED, id: 10748
;; flags: qr ra; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 2

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 1410
; OPT=15: 00 10 ("..")
;; QUESTION SECTION:
;www.mirtapbx.com.              IN      A

;; ADDITIONAL SECTION:
www.mirtapbx.com.       0       IN      TXT     "The OpenDNS service is currently unavailable in France and some French territories due to a court order under Article L.333-10 of the French Sport Code. See https://support.opendns.com/hc/en-us"

;; Query time: 1 msec
;; SERVER: 208.67.222.222#53(208.67.222.222)
;; WHEN: lun mar 30 21:31:15 BST 2026
;; MSG SIZE  rcvd: 257

In this case, it can be worth using

Cloudflare DNS (1.1.1.1)

Google Public DNS (8.8.8.8)

Quad9 (9.9.9.9)