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

By: Automated DNS for AWS instances using Route 53 « Cantina

Automated DNS for AWS instances using Route 53 « Cantina — Wed, 25 Jan 2012 18:26:52 +0000

[...] deal with this issue, some recommend running a BIND server on another instance. There are also some strategies which write out /etc/hosts on the instances using a cron job. Both [...]

By: vlad

vlad — Mon, 14 Nov 2011 15:15:39 +0000

Nice guide!

Can anyone share their opinion on how to update PTR records?

The problem here is that you don’t know what was the previous ip of an instance, so you can’t do

update del 10.xxx.xxx.xxx.in-addr.arpa. PTR

Input will be greatly appreciated!

By: Rangalal Gamage

Rangalal Gamage — Thu, 11 Aug 2011 11:09:47 +0000

We can write scripts to access AWS EC2 service and update /etc/host file using cron job. How ever most of the time we are using private IP’s to communicate between internal servers.

By: Ron west

Ron west — Fri, 24 Jun 2011 03:13:38 +0000

Shlomo,

Thanks for the response. I am probably using the internal DNS server differently. We would like to have a bunch of servers communicate with each other using friendly host names. Each of those servers would use the DNS server internally located on an EC2 instance to update their ips (using nsupdate).

The challenge is, that to get the servers to use the internal DNS server, each must be configured with the ip (namserver 10.x.x.x). However, that internal IP (to the EC2 DBS server – the one I so eloquently configured based on your awesome instructions) changes whenever I restart it. Even if it has an Elastic IP.

I think my only option is to build a script that updates this on all EC2 servers that I want to participate in this local domain.

Unless u have other thoughts.

By: Shlomo Swidler

Shlomo Swidler — Fri, 24 Jun 2011 03:03:03 +0000

@Ron West,

Check out the very first comment on this post.

By: Ron West

Ron West — Thu, 23 Jun 2011 17:20:32 +0000

Thank you for posting this – I have everything working as you described. The question I have is this:

On other EC2 instances, i want them to use this DNS server. However, since this DNS server is itself an EC2 instance its internal IP address changes (whenever a restart occurs).

I know that I can update the dhcpclient.conf to have prepended nameservers but what IP do I use? I can’t use the External IP (that won’t resolve) and the internal IP changes.

Any help would be greatly appreciated.

By: Ternary Labs Blog - Automatically Configure Hostname for New EC2 Instances

Ternary Labs Blog - Automatically Configure Hostname for New EC2 Instances — Wed, 15 Sep 2010 22:18:34 +0000

[...] technique was adapted from a more comprehensive example published by Marius Ducea. Post a comment or Leave a trackback Tweet [...]

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.