[dns-operations] aws.amazon.com zone has only one nameserver

[Yonghua Peng]

Hi,

As you see,

~$ idig aws.amazon.com ns
aws.amazon.com.         587     IN      NS      ns-911.amazon.com.

~$ idig aws.amazon.com soa
aws.amazon.com.         60      IN      SOA     ns-911.amazon.com. 
root.amazon.com. 1449536989 3600 900 7776000 60

~$ idig ns-911.amazon.com
ns-911.amazon.com.      197     IN      A       207.171.178.6

Do you know why this well known domain has only one nameserver, and it 
seems the nameserver has only one IP?

Thx.