Title: Amazon availability zones
Tags: amazon-web-services;amazon-s3;amazon-ec2;high-availability
Question: I'm fairly new to Amazon services and wondering what some of the best practices are for clustering/load balancing?

I have a load balancer in my colo (NJ) which may potentially be upgraded to Netscaler.

The application we're hosting on Amazon is nothing crazy and don't expect too much traffic.  We're looking at 2 linux instances that would run a Node JS application with a MongoDB replica set.  From what I understand, Amazon will evenly divide the traffic amongst the zones.  The end-users location has no effect on where they'll be distributed (ie if I have a server in the west coast and one in the east coast, the user in the east coast could be directed to either east or west).

```If I wanted to direct users traffic based on location, a global DNS solution would make more sense?
```

One server would be the master db and the other would be slave with data replicating to each other.

```Anybody have any experience with this and how is the network performance?
```

A question about EC2/S3

```EC2 Instances and S3 buckets can only communicate if they are in the same region, correct?
```


Here is the accepted answer: The load balancer only works within one region. If you want to balance traffic between different regions you will need to look at latency based routing in Route 53. Keep in mind that availability zone and region have different meanings within EC2

MongoDB replica set is a flexible master/slave configuration. If the primary instance fails, a secondary, based on configured priority can automatically become primary. Network within a region is fast, you will have some latency if you use multiple regions.

EC2 instance can access an s3 bucket in any region, you wont pay for outgoing bandwidth if both are in the same region.

Comment for this answer: what he is saying is true.


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