VMware KB: Update sequence for vSphere 5.1 Update 1 and its compatible VMware products
VMware KB: Update sequence for vSphere 5.5 and its compatible VMware products
Depending on what you see as the latest build 
The kbs have the links to the update guides further below in them for each component. Also be sure to check out the interop matrix (VMware Product Interoperability Matrixes) to see version compatibility between all components.