EMR has components running on internal ip's such as ip-172-23-53-101.ec2.internal. To resolve to the implied public/vpn IP's, setup dnsmasq
$ brew install dnsmasq
$ cp /usr/local/Cellar/dnsmasq/2.76/dnsmasq.conf.example /usr/local/etc/dnsmasq.conf
$ vim /usr/local/etc/dnsmasq.conf # add following to the end of the file
.....
....
# ashee: 03/19/2017
# AWS IPs see - http://stackoverflow.com/questions/28204678/dns-service-to-dynamically-resolve-subdomain-to-a-custom-ip-address
address=/ec2.internal/127.0.0.1
synth-domain=ec2.internal,0.0.0.0,255.255.255.255,ip-
$ sudo brew services start dnsmasq
$ networksetup -setdnsserver Wi-Fi 127.0.0.1 8.8.8.8 # or whatever dns server you had to begin with
$ dig ip-172-23-53-101.ec2.internal
; <<>> DiG 9.8.3-P1 <<>> @127.0.0.1 ip-172-23-53-101.ec2.internal
; (1 server found)
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 28487
;; flags: qr aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0
;; QUESTION SECTION:
;ip-172-23-53-101.ec2.internal. IN A
;; ANSWER SECTION:
ip-172-23-53-101.ec2.internal. 0 IN A 172.23.53.101
;; Query time: 0 msec
;; SERVER: 127.0.0.1#53(127.0.0.1)
;; WHEN: Mon Mar 13 19:25:03 2017
;; MSG SIZE rcvd: 63