f you want to find out domains DNS records like TXT, CNAME, MX, A or nameservers for the domain, there are numerous CLI tools for this task, I will show you two built in Ubuntu.
The easiest way is to use host command with -a option.
$ host -a google.com
Trying "google.com"
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 20315
;; flags: qr rd ra; QUERY: 1, ANSWER: 18, AUTHORITY: 0, ADDITIONAL: 2
;; QUESTION SECTION:
;google.com. IN ANY
;; ANSWER SECTION:
google.com. 82014 IN NS ns3.google.com.
google.com. 90 IN A 173.194.69.113
google.com. 144 IN MX 40 alt3.aspmx.l.google.com.
google.com. 90 IN A 173.194.69.100
google.com. 90 IN A 173.194.69.102
google.com. 144 IN MX 30 alt2.aspmx.l.google.com.
google.com. 82014 IN NS ns1.google.com.
google.com. 144 IN MX 20 alt1.aspmx.l.google.com.
google.com. 90 IN A 173.194.69.139
google.com. 144 IN MX 10 aspmx.l.google.com.
google.com. 90 IN A 173.194.69.101
google.com. 144 IN MX 50 alt4.aspmx.l.google.com.
google.com. 1478 IN TXT "v=spf1 include:_spf.google.com ip4:216.73.93.70/31 ip4:216.73.93.72/31 ~all"
google.com. 82014 IN NS ns2.google.com.
google.com. 275 IN AAAA 2a00:1450:4008:c01::71
google.com. 31 IN SOA ns1.google.com. dns-admin.google.com. 1516687 7200 1800 1209600 300
google.com. 90 IN A 173.194.69.138
google.com. 82014 IN NS ns4.google.com.
;; ADDITIONAL SECTION:
alt3.aspmx.l.google.com. 208 IN A 74.125.142.27
alt4.aspmx.l.google.com. 208 IN A 74.125.134.27
Received 498 bytes from 192.168.0.1#53 in 12 msThe second option is to use nslookup command with -type parameter. Change mx to a, or txt and see for your self.
$ nslookup -type=mx google.com
Server: 192.168.0.1
Address: 192.168.0.1#53
Non-authoritative answer:
google.com mail exchanger = 40 alt3.aspmx.l.google.com.
google.com mail exchanger = 50 alt4.aspmx.l.google.com.
google.com mail exchanger = 30 alt2.aspmx.l.google.com.
google.com mail exchanger = 20 alt1.aspmx.l.google.com.
google.com mail exchanger = 10 aspmx.l.google.com.
Authoritative answers can be found from:
alt3.aspmx.l.google.com internet address = 74.125.142.27
alt2.aspmx.l.google.com internet address = 173.194.64.27
aspmx.l.google.com internet address = 173.194.69.27
alt4.aspmx.l.google.com internet address = 74.125.134.27
alt1.aspmx.l.google.com internet address = 74.125.141.27alt1.aspmx.l.google.com internet address = 74.125.141.27
A very interesting command line tool you should also check out is dig.