What you learn, you forget 50% of it within 60 minutes and only retain 20% after a month.
The best way to learn and retain longer is reviewing/revising the content regularly and consistently
Brain is also a muscle, the more regularly you use it on some topic with reputation, the better you become at it. Instead of studying once a week for a longer time, try to study in small slots of time regularly and review it over and over again, so that it will penetrate deeper in your brain.
If you have many instances, managing the firewalls using Network ACL can be very useful. Otherwise, with Security group, you have to manually assign a security group to the instances.
State: Stateful or Stateless Security groups are stateful: This means any changes applied to an incoming rule will be automatically applied to the outgoing rule. e.g. If you allow an incoming port 80, the outgoing port 80 will be automatically opened. Network ACLs are stateless: This means any changes applied to an incoming rule will not be applied to the outgoing rule. e.g. If you allow an incoming port 80, you would also need to apply the rule for outgoing traffic.
Rules: Allow or Deny Security group support allow rules only (by default all rules are denied). e.g. You cannot deny a certain IP address from establishing a connection. Network ACL support allow and deny rules. By deny rules, you could explicitly deny a certain IP address to establish a connection example: Block IP address 188.8.131.52 from establishing a connection to an EC2 Instance.
Rule process order All rules in a security group are applied whereas rules are applied in their order (the rule with the lower number gets processed first) in Network ACL. i.e. Security groups evaluate all the rules in them before allowing a traffic whereas NACLs do it in the number order, from top to bottom.
Defense order Network ACL first layer of defense, whereas Security group is second layer of the defense for inbound/ingress traffic. Security group first layer of defense, whereas Network ACL is second layer of the defense for outbound/egress traffic.
Occurrence Subnet can have only one NACL, whereas Instance can have multiple Security groups.
Short answer is NO in recent times, here is why
The semicolon is used to separate statements, but it can be omitted if the statement is followed by a line break.
The semicolon is needed, only when you have two or more statements on the same line, not other wise 🙂
var i = 0; i++ // <-- semicolon obligatory
// (but optional before newline)
var i = 0 // <-- semicolon optional
i++ // <-- semicolon optional