32GB Server single node might not be a perfect candidate if you are planning for full fledged deployment and extensive testing, you can still leverage the same and build a basic lab. Follow below tips to downsize the VM's and i will highly recommend leveraging VMware HOL labs for higher end routing and cross VC use case deployments and testing. Combination of basic home labs and HOL will certainly help you.
https://communities.vmware.com/thread/571952
https://labs.hol.vmware.com/HOL/catalogs/catalog/877
http://www.routetocloud.com/2014/04/nsx-home-lab-part-1/
https://www.virten.net/2016/05/deploy-vmware-nsx-in-homelabs-with-limited-resources/
Good Luck With Your Exams !
Cheers,
Sree | VCIX-5X| VCAP-5X| VExpert 7x|Cisco Certified Specialist
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