shell:$ nslookup -timeout=2 -retry=1 'r4.res.office365.com'
Server:		75.98.161.224
Address:	75.98.161.224#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: 23.62.106.142
Name:	e40491.dscg.akamaiedge.net
Address: 23.62.106.138
Name:	e40491.dscg.akamaiedge.net
Address: 2600:1405:d400:8::173e:6a8e
Name:	e40491.dscg.akamaiedge.net
Address: 2600:1405:d400:8::173e:6a8a