[dns-operations] Cloudflare's DNS

[风河]

Just curious why cloudflare has that many DNS servers?
abby.ns.cloudflare.com
alex.ns.cloudflare.com
amy.ns.cloudflare.com
andy.ns.cloudflare.com
anna.ns.cloudflare.com
art.ns.cloudflare.com
ben.ns.cloudflare.com
beth.ns.cloudflare.com
bob.ns.cloudflare.com
brad.ns.cloudflare.com
carl.ns.cloudflare.com
coco.ns.cloudflare.com
cody.ns.cloudflare.com
dan.ns.cloudflare.com
dana.ns.cloudflare.com
dave.ns.cloudflare.com
dawn.ns.cloudflare.com
dina.ns.cloudflare.com
dora.ns.cloudflare.com
duke.ns.cloudflare.com
ed.ns.cloudflare.com
edna.ns.cloudflare.com
elle.ns.cloudflare.com
elsa.ns.cloudflare.com
emma.ns.cloudflare.com
eric.ns.cloudflare.com
erin.ns.cloudflare.com
eva.ns.cloudflare.com
fay.ns.cloudflare.com
fred.ns.cloudflare.com
gabe.ns.cloudflare.com
gail.ns.cloudflare.com
gina.ns.cloudflare.com
greg.ns.cloudflare.com
hank.ns.cloudflare.com
hugh.ns.cloudflare.com
ian.ns.cloudflare.com
igor.ns.cloudflare.com
iris.ns.cloudflare.com
isla.ns.cloudflare.com
ivan.ns.cloudflare.com
ivy.ns.cloudflare.com
jack.ns.cloudflare.com
jake.ns.cloudflare.com
jay.ns.cloudflare.com
jean.ns.cloudflare.com
jeff.ns.cloudflare.com
jill.ns.cloudflare.com
jim.ns.cloudflare.com
josh.ns.cloudflare.com
kara.ns.cloudflare.com
kate.ns.cloudflare.com
kay.ns.cloudflare.com
ken.ns.cloudflare.com
kim.ns.cloudflare.com
kip.ns.cloudflare.com
lady.ns.cloudflare.com
lara.ns.cloudflare.com
leah.ns.cloudflare.com
lee.ns.cloudflare.com
lily.ns.cloudflare.com
lisa.ns.cloudflare.com
lola.ns.cloudflare.com
lucy.ns.cloudflare.com
mark.ns.cloudflare.com
mary.ns.cloudflare.com
matt.ns.cloudflare.com
max.ns.cloudflare.com
may.ns.cloudflare.com
nina.ns.cloudflare.com
noah.ns.cloudflare.com
norm.ns.cloudflare.com
olga.ns.cloudflare.com
pam.ns.cloudflare.com
pat.ns.cloudflare.com
paul.ns.cloudflare.com
pete.ns.cloudflare.com
phil.ns.cloudflare.com
ray.ns.cloudflare.com
rick.ns.cloudflare.com
rita.ns.cloudflare.com
rob.ns.cloudflare.com
rose.ns.cloudflare.com
roxy.ns.cloudflare.com
ruth.ns.cloudflare.com
sam.ns.cloudflare.com
sara.ns.cloudflare.com
seth.ns.cloudflare.com
sid.ns.cloudflare.com
sla.ns.cloudflare.com
sue.ns.cloudflare.com
theo.ns.cloudflare.com
tim.ns.cloudflare.com
todd.ns.cloudflare.com
tom.ns.cloudflare.com
uma.ns.cloudflare.com
vera.ns.cloudflare.com
walt.ns.cloudflare.com
will.ns.cloudflare.com
woz.ns.cloudflare.com
zara.ns.cloudflare.com
zoe.ns.cloudflare.com

And the IP addresses for those NS are in the same networks (maybe two 
/24 networks).
$ cat cfdns.txt|while read LINE;do dig +short $LINE;done|sort -u
173.245.58.100
173.245.58.101
173.245.58.102
173.245.58.103
173.245.58.104
173.245.58.105
173.245.58.106
173.245.58.107
173.245.58.108
173.245.58.109
173.245.58.110
173.245.58.111
173.245.58.112
173.245.58.113
173.245.58.114
173.245.58.115
173.245.58.116
173.245.58.117
173.245.58.118
173.245.58.119
173.245.58.120
173.245.58.121
173.245.58.122
173.245.58.123
173.245.58.124
173.245.58.125
173.245.58.126
173.245.58.127
173.245.58.128
173.245.58.129
173.245.58.130
173.245.58.131
173.245.58.132
173.245.58.133
173.245.58.134
173.245.58.135
173.245.58.136
173.245.58.137
173.245.58.138
173.245.58.139
173.245.58.140
173.245.58.141
173.245.58.142
173.245.58.143
173.245.58.144
173.245.58.145
173.245.58.146
173.245.58.147
173.245.58.148
173.245.58.149
173.245.58.152
173.245.58.169
173.245.58.212
173.245.59.100
173.245.59.101
173.245.59.102
173.245.59.103
173.245.59.104
173.245.59.105
173.245.59.106
173.245.59.107
173.245.59.108
173.245.59.109
173.245.59.110
173.245.59.111
173.245.59.112
173.245.59.113
173.245.59.114
173.245.59.115
173.245.59.116
173.245.59.117
173.245.59.118
173.245.59.119
173.245.59.120
173.245.59.121
173.245.59.122
173.245.59.123
173.245.59.124
173.245.59.125
173.245.59.126
173.245.59.127
173.245.59.128
173.245.59.129
173.245.59.130
173.245.59.131
173.245.59.132
173.245.59.134
173.245.59.135
173.245.59.136
173.245.59.137
173.245.59.138
173.245.59.139
173.245.59.140
173.245.59.141
173.245.59.142
173.245.59.143
173.245.59.144
173.245.59.145
173.245.59.146
173.245.59.147
173.245.59.148
173.245.59.149
173.245.59.150
173.245.59.189
173.245.59.4

Have they been using these many servers to improve the capibility of 
anti-DDoS?
Thanks.