Dig command repated SERVER value

I'm exploring the various options of dig command. I have disabled all output except the stats section:

$ options="+noanswer +nocmd +nocomments +stats"

$ dig example.com $options
;example.com.           IN  A
;; Query time: 41 msec
;; SERVER: 75.75.75.75#53(75.75.75.75)
;; WHEN: Wed Apr 01 11:59:25 MDT 2020
;; MSG SIZE  rcvd: 56

$ dig stackoverflow.com $options
;stackoverflow.com.     IN  A
;; Query time: 49 msec
;; SERVER: 75.75.75.75#53(75.75.75.75)
;; WHEN: Wed Apr 01 11:59:43 MDT 2020
;; MSG SIZE  rcvd: 110

Why these two different domains return the same SERVER? Every domain that I have tried return the same SERVER value.

Solution

;; SERVER: 75.75.75.75#53(75.75.75.75)

Is the DNS Name-server used during the dig command.

You can confirm this by checking which name-server your computer uses;

$ dig +noanswer +nocmd +nocomments +stats example.com
...
;; SERVER: 172.18.0.254#53(172.18.0.254)
...

$ cat /etc/resolv.conf  | tail -n 1
nameserver 172.18.0.254

_{I'm using a local custom DNS server, therefore the local ip ;)}