Simple explanation
Two related must-know topics: how cloud connectivity works, and the specific ports/protocols every networking professional is expected to know cold.
Technical explanation
Cloud concepts: service models (IaaS/PaaS/SaaS — same as covered in Security+), deployment models (public, private, hybrid, community), and connectivity options: VPN (encrypted tunnel over the public internet to reach cloud resources), direct connect (a private, dedicated physical connection to a cloud provider, bypassing the public internet for better performance/security).
Common ports and protocols (know these cold): | Port | Protocol | Purpose | |---|---|---| | 20/21 | FTP | File Transfer Protocol (data/control) | | 22 | SSH | Secure Shell — encrypted remote access | | 23 | Telnet | Unencrypted remote access (legacy, avoid) | | 25 | SMTP | Simple Mail Transfer Protocol — sending email | | 53 | DNS | Domain Name System | | 67/68 | DHCP | Dynamic Host Configuration Protocol | | 80 | HTTP | Unencrypted web traffic | | 110 | POP3 | Retrieving email (older, downloads and often deletes from server) | | 143 | IMAP | Retrieving email (keeps mail on server, syncs across devices) | | 443 | HTTPS | Encrypted web traffic | | 3389 | RDP | Remote Desktop Protocol |
Traffic types: unicast (one sender, one receiver), multicast (one sender, a specific group of receivers), broadcast (one sender, every device on the local segment), anycast (one sender, delivered to the nearest of multiple possible receivers).
Synonyms / related terms
| Term | Means | |---|---| | SMTP | Simple Mail Transfer Protocol | | RDP | Remote Desktop Protocol | | Direct Connect | AWS's specific name for a dedicated cloud connection (a generic concept across providers) |
Concept Check
"A network engineer needs a private, high-bandwidth, dedicated connection to a cloud provider, bypassing the shared public internet entirely." A standard VPN doesn't satisfy this — a VPN still traverses the public internet, just encrypted. The requirement for a dedicated, private physical path specifically calls for a direct connect-style connection.
Interview-style Q&A
Q: Why would an organization still use POP3 today, given IMAP's advantages? A: "Rarely for a good reason at this point — IMAP's server-side sync across multiple devices is almost universally preferred. POP3 might still appear in a legacy system or a very simple single-device setup where the mail should be downloaded and removed from the server, but for most modern use cases IMAP is the better default."
Memory trick
"SSH is 22, Web is 80/443, Mail comes in on 110/143, Mail goes out on 25" — grouping ports by function (remote access, web, receiving mail, sending mail) makes them stick better than memorizing a flat list.