How do I host a public domain if I have to DHCP an IP address?
You can use a dynamic DNS service, such as DynDNS or ZoneEdit.
How do I handle time synchronization between instances?
You can set up NTP (the Network Time Protocol) which does this for you. You can find more
information at This is particularly important if you plan on using any of
Amazon's web services (such as Amazon S3 or Amazon EC2) from within an instance, since
requests to these services need to be timestamped.
Can I use my own kernel?
Not at present.
Can I get a bigger/smaller/differently optimized virtual machine?
Not at present. For now, if you need more capacity launch more instances.
Is there a REST interface to Amazon EC2?
Not at present. For now, you will have to use the SOAP API or the provided API command line
How does Amazon EC2 handle load balancing?
With a service as flexible as Amazon EC2, customers can launch any number of load balancing
systems within Amazon EC2. The load balancing instances can forward traffic to other systems.
There are several open source solutions that are in wide use.
How do I monitor my systems?
Amazon EC2 currently only provides the most basic monitoring. You can tell from
DescribeInstances whether we believe your instance is running or not. However, you may regard
your systems running in Amazon EC2 as your data center, and so any monitoring instrumentation
that you wish to include on the systems be it SNMP or some other mechanism is entirely up to
Is there any way for an instance to discover its own instance ID?
Not at present. For now you can get the instance ID by bundling an image with your credentials
and calling ec2-describe-instances. The return values contain both the hostname (which the
instance knows) and the instance ID.
The following command should do the trick (assuming the command line tools have been
configured correctly): ec2-describe-instances | grep $HOSTNAME | awk '{print
Amazon EC2
Developer Guide
Can I pass arbitrary configuration values to an instance at launch time?
Not at present.
Is there a way to run a script on instance termination?
Not with any reliability. Amazon EC2 tries to shut an instance down cleanly (in which case
normal system shutdown scripts will run), but there is only a short time available for things to
happen and in some cases (hardware failure, for example) this does not happen. Since there is no
entirely reliable way to ensure shutdown scripts run, it is best to have a strategy in place to deal
with abnormal terminations.
Why do I get keep getting "Request has expired" errors?
To reduce the risk of replay attacks our requests include a timestamp. This, along with the most
important parts of the request, is signed to ensure the message (including the timestamp) can't be
modified without detection.
If the difference between the timestamp in the request and the time on our servers is larger than 5
minutes the request is deemed too old (or too new) and an error is returned.
You need to ensure that your system clock is accurate and configured to use the correct timezone.
NTP is a good way to do this.
Amazon EC2
Developer Guide
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