How to view and modify DNS configuration in a Linux system

DNS refers to the computer domain Name System, which consists of a domain name resolver and a domain name server, which provides DNS services to DNS servers. General operation of the domain name preferably has two or more DNS servers, respectively known as the primary domain name server and from the domain name server, where the second DNS server is often used for failover. Many users do not know how to view and modify DNS, so the small set next to you on the Linux system to view and modify the DNS configuration methods.

　　To view DNS information for a server:

1: View/etc/resolv.con files

[Root@localhost ~]# cat/etc/resolv.conf

NameServer 192.168.xxx.xxx

#search Localdomain

[Root@localhost ~]#

2: Use the nslookup command to view DNS information

[root@localhost ~]# nslookup 127.0.0.1 | grep Server

Server:192.168.xxx.xxx

[Root@localhost ~]#

3: Use the DIG command to view DNS information

[Root@localhost ~]# Dig

; "" "" "DiG 9.3.6-p1-redhat-9.3.6-16.p1.el5" ""

;; Global Options:printcmd

;; Got Answer:

;; -"The HEADER"-Opcode:query, Status:noerror, id:36888

;; Flags:qr Rd RA; Query:1, Answer:13, authority:0, Additional:3

;; Question section:

;。 In NS

;; ANSWER section:

。 86163 in NS m.root-servers.net.

。 86163 in NS a.root-servers.net.

。 86163 in NS j.root-servers.net.

。 86163 in NS l.root-servers.net.

。 86163 in NS e.root-servers.net.

。 86163 in NS d.root-servers.net.

。 86163 in NS k.root-servers.net.

。 86163 in NS f.root-servers.net.

。 86163 in NS h.root-servers.net.

。 86163 in NS c.root-servers.net.

。 86163 in NS g.root-servers.net.

。 86163 in NS b.root-servers.net.

。 86163 in NS i.root-servers.net.

;; ADDITIONAL section:

A.root-servers.net. 3599 in A 112.4.20.71

B.root-servers.net. 86163 in A 192.228.79.201

I.root-servers.net. 86173 in A 192.36.148.17

;; Query Time:8 msec

;; server:192.168.xxx.xxx#53 (192.168.XXX.XXX)

;; When:sat APR 16 07:34:37 2016

;; MSG SIZE rcvd:289

[Root@localhost ~]# Dig | grep SERVER: | awk-f# ' {print $} ' | Awk-f: ' {print $} '

192.168.xxx.xxx

4: Some other ways to view DNS information

There are other ways to see the DNS configuration information on the server, as shown below, but these methods, due to environmental restrictions, I have not verified, for reference only.

Nm-tool | grep DNS

NMCLI Dev list iface eth0 | grep IP4

　　Modifying DNS information for a server

Modifying a DNS server is simple, and you only need to modify the/etc/resolv.conf configuration file. The answer is no if you need to restart some services to modify DNS. The changes will take effect immediately and do not require any additional processing.