Comments on: HowTo update DNS hostnames automatically for your Amazon EC2 instances

By: HowTo update DNS hostnames automatically for your Amazon EC2 instances › ec2base

Mon, 11 Jan 2010 23:20:13 +0000

[...] http://www.ducea.com/2009/06/01/howto-update-dns-hostnames-automatically-for-your-amazon-ec2-instanc... [...]

By: Shlomo Swidler

Shlomo Swidler — Mon, 11 Jan 2010 16:20:44 +0000

The user-data URL returns a 404 only if no user-data was supplied when the instance launched.

By: Federico

Federico — Tue, 17 Nov 2009 23:35:31 +0000

Also, it’s important to note that curl http://169.254.169.254/latest/user-data sometimes returns a 404.

By: links for 2009-06-02 « Bloggitation

links for 2009-06-02 « Bloggitation — Tue, 02 Jun 2009 07:03:37 +0000

[...] HowTo update DNS hostnames automatically for your Amazon EC2 instances | MDLog:/sysadmin (tags: amazon ec2 dns 247up sysadmin) [...]

By: - Marius -

- Marius - — Mon, 01 Jun 2009 15:15:22 +0000

@John: thanks for your note. Actually I knew that, not sure why I always preferred to use A records for this… Still your suggestion works just fine even without elastic IPs, using a similar (simpler) script as described above that will register a single CNAME record instead.

Cheers,
- Marius -

By: John Ferlito

John Ferlito — Mon, 01 Jun 2009 14:37:48 +0000

While useful in some situations this isn’t strictly necessary if you are using elastic IPs.

If you have a static IP of which the domain name is say ec2-75-101-128-23.compute-1.amazonaws.com. Then while from the internet it resolves to 75.101.128.23. As long as you use Amazon’s DHCP allocated name servers when you look it up inside EC2 it will always resolve to the private address.

So I setup my DNS so that blah.mydomain.com is a CNAME to ec2-75-101-128-24.compute-1.amazonaws.com which will then always resolve to either the public or private IP depending on where the lookup is done.