Но их родной таки 64.74.223.42
dig ncatlab.org

; <<>> DiG 9.4.3-P5 <<>> ncatlab.org
;; global options: printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 24731
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 5, ADDITIONAL: 0

;; QUESTION SECTION:
;ncatlab.org. IN A

;; ANSWER SECTION:
ncatlab.org. 1800 IN A 64.74.223.42

;; AUTHORITY SECTION:
ncatlab.org. 3600 IN NS dns4.name-services.com.
ncatlab.org. 3600 IN NS dns1.name-services.com.
ncatlab.org. 3600 IN NS dns3.name-services.com.
ncatlab.org. 3600 IN NS dns2.name-services.com.
ncatlab.org. 3600 IN NS dns5.name-services.com.

я не поленился сделать
dig ncatlab.org @dns[1-5].name-services.com

;ncatlab.org. IN A

;; ANSWER SECTION:
ncatlab.org. 1800 IN A 64.74.223.42