MCSE

A subnet mask allows you to identify which part of an IP address is reserved for the network, and which part is available for host use

Private IP is non-routable
Public IP is routable.

The Address (A) record associates a domain name with an IP address, which is the primary purpose of the DNS system.

PTR records resolve IP addresses into hostnames

An MX (mail exchange) record can be used to point your domain name email services to your own mail server

Aliasing Names (CNAME)
The Canonical Name (CNAME) record is used to create aliases that point to other names.

The DNS zone file is a specially formatted file containing information about a domain's resources such as mail servers and web servers. The primary purpose of a zone file is to provide the information necessary to convert an alphanumeric domain name into a numeric IP address.

Port 53

Client - DHCPDISCOVER
Server - DHCPOFFER
Client - DHCPREQUEST
Server - DHCPACK

Hubs are repeater devices designed to replicate a signal on one port and replicating it on all other ports.

A network switch is a small hardware device that joins multiple computers together within one local area network (LAN). Technically, network switches operate at layer two (Data Link Layer) of the OSI model.
Unlike hubs, network switches are capable of inspecting data packets as they are received, determining the source and destination device of that packet, and forwarding it appropriately

Application
Presentation
Session
Transport
Network
Data Link
Physical

Client UDP port 68.
The server replies on UDP 67

identifies the authoritative DNS servers for a domain