go
mx-cluster2.one.com has one IP number , which also has a corresponding reverse pointer. mx2.sterup.dk, mx2.optiekmonset.be, mx-cluster2.b-one.net and mx-cluster2.one.com.b-one.net point to the same IP. whi.se, awe.se, tmk.se, nke.no, rld.be and at least 100 other hosts use this as a mailserver. one.com is a domain controlled by two nameservers at b-one-dns.net. They are on the same IP network. Incoming mail for one.com is handled by two mailservers at one.com themselves. They are on the same IP network. one.com has one IP number. mx-cluster2.one.com is hosted on a server in Denmark.

mx-cluster2.one.com
a records
 
+ 91.198.169.11 91.198.169.0/24 AS16245 -
+ --- -

one.com
a records
 
+ 195.47.247.252 195.47.247.0/24 AS16245  
+ ---  
ns-soa records
a.b-one-dns.net
+ 195.47.247.13 195.47.247.0/24 AS16245 -
+ --- -
ns records
a.b-one-dns.net
+ 195.47.247.13 195.47.247.0/24 AS16245 -
+ --- -
b.b-one-dns.net
+ 195.47.247.14 195.47.247.0/24 AS16245 -
mx records
mx-cluster1.one.com
+ 91.198.169.10 91.198.169.0/24 AS16245 -
+ --- -
mx-cluster2.one.com
+ 91.198.169.11 91.198.169.0/24 AS16245 -
ip numbers of host
91.198.169.11
ptrs of ip numbers
mx-cluster2.one.com
ip numbers using ptr to this host
91.198.169.11
hostnames sharing ip with a-records
mx-cluster2.b-one.net
mx-cluster2.one.com.b-one.net
mx2.optiekmonset.be
mx2.sterup.dk
domains using this as mailserver
1251.se
4web.se
aaap.dk
acherentals.be
acord.se
adec.se
ahl-lejrskole.dk
alabarn.se
allsystemsred.com
amab.com
ambientmedia.se
anna-lena.se
archers.nl
aste.se
atletica-tri.dk
awe.se
b-one.net
b-one.nu
bad-varme.dk
batformedling.com
bgnews.no
bkvibro.net
bluetigers.se
bonanova.com
bwa-helsinki.com
calay.be
cannonballforums.se
clawfinger.se
corefiles.com
daniel87.de
dansk-klima-energi.dk
daycruiser.dk
de4.biz
debergjes.nl
deracketeers.nl
develiogludag.com
digi-demo.dk
digitalkopia.se
dittfoto.se
drottningenskalla.se
escandinavo.com
firmalegend.dk
fmjk.dk
fosenborg.com
fotografer.org
fuzzyfish.net
gamezoo.de
haggman.se
harmonika.dk
hassemans.se
hittagolfresan.se
hokeren.dk
horlogehuis.com
hsi.se
infocon.se
intermag.se
jonasl.se
kackelstugan.com
kantstrasse100.de
kedrissos.dk
konferansen.com
lafamilleheureuse-liege.be
lfsv.dk
lind-larsen.org
loewenschuetzen.de
lundhenry.com
maptech.dk
marineregimentet.dk
mayonai.se
mekuli.com
mhw.dk
michael-shawn-lewis.com
minnebergs.se
musikfest.se
nke.no
novation.dk
ns1.b-one.net
ns1.b-one.nu
objektiv.dk
one.com
orchidehuset.se
pecke.se
radicalride.dk
recklessdoom.net
relek.se
restaurangalvan.se
rld.be
rotmotaverken.se
rydholm.se
safead.se
sany.se
schreibblog.eu
selvbyg-traehuse.dk
sic.no
sm-data.se
smkhedemora.com
snc.se
soundrise.se
ss-spejderne.dk
stenhuset.dk
studiofolkhemmet.com
svenskridsport.com
swepex.se
tanzsport-paderborn.de
thebrinchs.com
timmerhuggaren.se
tmk.se
tradservice.se
united-angels.de
vagspel.se
vagteksperten.dk
vebab.se
viralvideo.dk
vittorias.se
vivero.se
volleynor.no
whi.se
wohnflair.com
xrc.se
ymse.com
domains using this as mailserver under another name
optiekmonset.be
sterup.dk