Yes three are many topics that are challenging for students to understand and some of the topics they are hard from A+ to Security for exam, DNS TXT records (SPF/DKIM/DMARC) and the we have subneting in CompTIA Network plus, Cryptography in Security plus.... I use analogies.
Imagine your email domain is a house, and the internet is a big neighborhood
- SPF = List of Approved Delivery Guys
- DKIM = Signature on the package, puts a tamper-proof signature on each mail you send
- DMARC = The House Rules on What to Do with fake mail, decides what happens to suspicious mail
For Subnetting,
Imagine a big city (a network) with thousands of houses (IP addresses). If the city is too big, managing houses becomes confusing.So we create suburbs/subdivisions (subnets)
Cryptography- Locking a Message in a Box with a Key, anything is secure because of it
Though not enough info but it assist students to understand underlying idea.