What is the Difference between Azure Load Balancer and Application Gateway.

Azure Application Gateway

• It provides application delivery controller (ADC) as a service and offer various Layer 7 load-balancing capabilities.
• It is on top of load balancing the workloads, can make routing decisions based on URI path or host headers. For example, route traffic based on the incoming URL. 
• If /images are in the inbound URL we can route the traffic to a specific set of servers (or pool) configured for images. If /video is in the URL, that traffic is routed to another pool.
• It can be used to do TLS/SSL termination. TLS/SSL termination can be useful to allow unencrypted traffic between Application Gateway and backend servers.
• Application Gateway also supports end-to-end TLS/SSL encryption.
• It includes a web application firewall called Web application firewall (WAF) that protects workload from common exploits like SQL injection attacks or cross-site scripting attacks, etc

Azure Load Balancer

• Azure Load Balancer is a high-performance, low-latency Layer 4 load-balancing service (inbound and outbound) for all UDP and TCP protocols. 
• It is built to handle millions of requests per second. 
• It is zone-redundant for ensuring high availability across Availability Zones.
• Load balancing refers to evenly distributing load (incoming network traffic) across a group of backend resources or servers.
• It distributes inbound flows that arrive at the load balancer’s front end to backend pool instances. 
• These flows are according to configured load balancing rules and health probes. 
• The backend pool instances can be Azure Virtual Machines or instances in a virtual machine scale set.
• It’s using TCP/UDP load balancing and port forwarding engine only. 
• It simply routes traffic based on source IP address and port to a destination IP address and port.

Azure Load Balancer types:

• Public load balancer:-

1. It is used outbound connections for virtual machines (VMs) inside virtual network. 
2. These connections are accomplished by translating their private IP addresses to public IP addresses. 
3. Public Load Balancers are used to load balance internet traffic to VMs.

• Private load balancer:-

1. It is used where private IPs are needed at the frontend only. 
2. It is used to load balance traffic inside a virtual network.