Add Datadog and ArgoCD questions

As well as exercises.

topics/datadog/README.md

@@ -1,5 +1,48 @@
 # DataDog
 
+- [DataDog](#datadog)
+  - [Questions](#questions)
+    - [Basics](#basics)
+
 ## Questions
 
-TODO
+### Basics
+
+
+<details>
+<summary>Describe at least three use cases for using something like Datadog. Can be as specific as you would like</summary><br><b>
+
+* Monitor instances/servers downtime
+* Detect anomalies and send an alert when it happens
+* Service request or response latency
+
+</b></details>
+
+<details>
+<summary>What ways are there to collect or send data to Datadog?</summary><br><b>
+
+* Datadog agent installed on the device or location which you would like to monitor
+* Using Datadog API
+* Built-in integrations
+
+</b></details>
+
+<details>
+<summary>What is a host in regards to Datadog?</summary><br><b>
+
+Any physical or virtual instance that is monitored with Datadog. Few examples:
+
+- Cloud Instance, Virtual Machine
+- Bare metal node
+- Platform or service specific nodes like Kubernetes node
+
+Basically any device or location that has Datadog agent installed and running on.
+</b></details>
+
+<details>
+<summary>What is a Datadog agent?</summary><br><b>
+</b></details>
+
+<details>
+<summary>What are Datadog agents?</summary><br><b>
+</b></details>