Self-study and home lab work, labelled as such because it has never been a network engineering role and there is no certification and no production configuration behind it.
- Built many PCs from scratch for myself, family and friends, matching the specification to what the person actually needed and the case and fans to what they wanted it to look like.
- Experimented across macOS, Windows and Linux.
- Recently started home-labbing properly and standing up a local personal server.
The networking
Layer 2 and Layer 3, covering VLANs and 802.1Q trunking, switching, MAC and ARP, STP and RSTP, link aggregation, IP addressing, subnetting and CIDR, static routing, OSPF concepts, NAT and PAT, ACLs, zone segmentation and TCP and UDP traffic analysis.
All of that is self-study and home lab work. What it buys me is that infrastructure conversations do not stop at the application boundary.
DNS is the exception and carries full weight, having been applied professionally at Prospa to support large-scale partner integration.
Taken together with the fifteen years of building and fixing things, this is a long run of self-directed practice, not a recent interest.