Wednesday, May 15, 2013

EC2 (classic) instance hostname is not hostname and is not hostname


This is the results from wget and hostname at command line.
1. wget -q -O - http://169.254.169.254/latest/meta-data/public-hostname
Output ---> ec2-50-13-20-1.compute-1.amazonaws.com
2. wget -q -O - http://169.254.169.254/latest/meta-data/hostname
Output-->   ip-10-222-1-241.ec2.internal
3. wget -q -O - http://169.254.169.254/latest/meta-data/local-hostname
output--->ip-10-222-1-241.ec2.internal
4. wget -q -O - http://169.254.169.254/latest/meta-data/local-ipv4
output--->10.222.1.241
5. wget -q -O - http://169.254.169.254/latest/meta-data/public-ipv4
50.13.20.1
6. [root@wls1 ~]# hostname  ---> linux command line
wls1.labs.oracleweblogic.com

Someone changed the host name after boot or at boot time using user-data or another method.  Normally you would see:


1. wget -q -O - http://169.254.169.254/latest/meta-data/hostname
Output ---> ip-14-222-22-28.us-west-2.compute.internal

2. hostname: hostname ---> linux command line
ip-14-222-22-28


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