Azure Basics · Module 04

Virtual Networking – VNets, IPs, NSGs, Firewall and DNS

Build VNets with non-overlapping subnets, assign public/private IPs, filter traffic with NSGs, control it centrally with Azure Firewall and resolve names with Azure DNS.

Practice interactively →

What you will learn

• Design non-overlapping address spaces and subnets
• Choose public/private IPs, Standard SKU, static/dynamic
• Write NSG rules with the right priority and understand subnet vs NIC NSGs
• Tell NSGs from Azure Firewall and its three rule types
• Create a public DNS zone, delegate it and use private DNS zones

Lessons

1. Virtual Networks and Subnets

   A VNet is your private network in Azure with one address space; subnets split the VNet, must not overlap, and Azure reserves 5 addresses in each.

2. Public and Private IP Addresses

   Private IPs work inside VNets and on-premises; public IPs reach the Internet and now only use the Standard SKU (always Static, zone-redundant). IPs attach to NICs, not directly to VMs.

3. Network Security Groups (NSGs)

   An NSG is a list of allow/deny rules evaluated by priority (lower number first) attached to a subnet or NIC; inbound traffic must be allowed by both the subnet NSG and the NIC NSG.

4. Azure Firewall

   Azure Firewall is a stateful firewall service placed in a hub VNet that filters centrally with NAT, network and application (FQDN) rules; unlike NSGs, which only filter L3/L4 at a subnet/NIC.

5. Azure DNS — Zones, Delegation and Private Zones

   A public DNS zone holds a domain's records and is delegated with all 4 Azure name servers; a private DNS zone resolves names inside VNets once it is linked to them.