shell:$ nslookup -timeout=2 -retry=1 'r4.res.office365.com'
Server:		1.1.1.1
Address:	1.1.1.1#53

Non-authoritative answer:
r4.res.office365.com	canonical name = r4.res.office365.com.edgekey.net.
r4.res.office365.com.edgekey.net	canonical name = e40491.dscg.akamaiedge.net.
Name:	e40491.dscg.akamaiedge.net
Address: 23.199.54.233
Name:	e40491.dscg.akamaiedge.net
Address: 23.199.54.229
Name:	e40491.dscg.akamaiedge.net
Address: 2600:1408:5400:31::17c3:2504
Name:	e40491.dscg.akamaiedge.net
Address: 2600:1408:5400:31::17c3:2509