Clustering, sharding and other multi-server setups
Ghost does not support load-balanced clustering or multi-server setups of any description, there should only be one Ghost instance per site.
The recommended scaling and performance approach is to put a cache and/or CDN in front of your blog; pages generated by Ghost are essentially static so there should be very little traffic hitting your Ghost server with a well configured cache.
If you try to run Ghost on multiple nodes, you will run into errors such as
Response code 405 (Method Not Allowed) - and find that the Ghost service needs to be constantly restarted for any content to reliably appear.
The correct solution is to reduce your infrastructure to a single node and use caching.