Networking Flashcards
What IP ranges can be used?
/16 (65532) to /28 (16)
What IPs are reserved and for what purpose?
.0 -> Networking .1 -> VPC Router .2 -> DNS Server .3 -> Future use .255 -> Broadcasting (reserved to not allow the user)
What are the parts of an ENI?
One or more IPv4 address One or more IPv6 address Security Groups MAC address Source/Destination checks
What is eth0?
The primary network interface
Cannot be detached from the instance. But there can be additional network interfaces. (up to a limit)
What needs to be considered using an Elastic IP?
- IPv6 is not supported (atm)
- When associating an EIP the currently attached IP will be send back to the IP pool
- The DNS host name will be changed
- Theres no charge for using an EIP but a charge when it is not used
- It is regional
What are VPC Flow Logs?
Captures information of IP traffic in/out of the network.
Can be retrieved in the CloudWatch Logs
What are the advantages of Direct Connect?
- Reduces bandwith costs
- Consistent network performance
- Private connectivity to AWS
- Network scaling possibilities
How to set up Direct Connect?
- Submit Connection Request
- Download and send Letter of Authorization and Connecting
- Create Virtual Interface
- Download Router Configuration
Options for a VPN?
- Virtual Private Gateway
- VPN CloudHub
- Software VPN
Functions of Route53?
- Register domain names
- Route internet traffic to the resources to the domain
- Check the health of the resources
What are the three types of health checks?
- Health of a specific resource, like web servers
- Status of CloudWatch alarms
- Status of other health checks
Can you have a CF distribution with your own domain?
Yes
What are Regional Edge Caches?
Between Origin and Edge Location.
Larger Cache with longer caching times
What can be an Origin Server?
AWS resources such as S3, EC2, Elastic Load Balancing.
Or something outside of AWS.
What is Private Content in CloudFront?
Enables to set access rights for the users, like signed URLs
What is Device Detection
Detects the device and therefore can deliver different content based on that
What is Geo Targeting?
Detects the country and can deliver content based on that
How are Query String Parameters handled in CF?
Per default query parameters are not used for the origin - it can be configured to use those
What is Object Versioning and Cache Invalidation?
Object Versioning: New Filename each time, so until deleted the old version is still online
Cache Invalidation: Old version is removed and replaced by the new version
What is Zone Apex Support?
You can use your own domain for the distribution
What is the primary cause(s) of an EC2 network bottleneck?
Geographical proximity, EC2 instance size, and lack of enhanced network features
What AWS VPC feature would you choose to connect and improve network performance between two VPCs without transiting the public internet?
VPC Peering is a way to connect two VPCs and improve network performance.
What information does a VPC Flow Log capture?
VPC Flow Logs capture IP traffic as metadata for a VPC.
What connection speeds does AWS Direct Connect provide?
1 Gbps
10 Gbps
What step is used to assign an Elastic IP (EIP) to an instance?
Association is the step used to assign an EIP to an instance.
Which of the following does a dedicated connection require?
Single-mode fiber
Dual-mode fiber
Single-mode fiber
Which of these is not a benefit of SSL Offloading?
Scalable HTTPS/SSL from a singular point
Improved networking
Ease of certificate management
Increased processing performance with SSL
SSL Offloading does not lead to improved networking.
Which of these is not a benefit of Amazon CloudFront?
Increased CPU performance
Increased network performance
High transfer speeds from the origin
Low latency
Amazon CloudFront is a CDN, and it does not increase the CPU performance of an instance. The instance workload may lessen due to the request of cached content from CloudFront, but this does not mean the CPU performance of an instance has been increased.
Which three make up the components of a load-balancer?
Load-balancer, Target Group, and Listener
Which three are the components of an AWS VPN?
VPN Connection
Customer Gateway
Virtual Private Gateway
What can the ALB do that the Network LB cannot?
Look at the content of a package (for example the header) and make decisions based on it
When should you pre warm your LB and how?
When there’s a planned spike in Traffic you can contact AWS to increase the capacity of your LB
What should be done when a 460 client closed connection error occured?
The user should increase the timeout
Describe the three placement group types and their advantages
Cluster: all Instances are in one AZ and have a 10GBs connection
Partition: Instances are created in segments, all located in separate racks (and can be in multiple AZs) - for distributes workloads
Spread: Each instance is in a separate rack
What is a Cache-Hit-Ratio?
Number of request served by the cache, compared to the origin
What can be done to have a better Cache-Hit Ratio?
- Longer cache time
- Query Parameter cache (beware: they are case sensitive)
- Caching based on cookie values
- Caching based on Request Header
- Remove Accept-Encoding Header (when no need for compression)
What are the two types of VPC endpoints?
Interface endpoint: powered by AWS PrivateLink
Gateway endpoint: S3/Dynamo DB
When connection two VPCs, how many Peering connections are needed?
Just one
What is Dual-Stack mode?
It runs IPv4 and IPv6
What is Connection Draining?
A setup done in the console or CLI that causses the LB to stop sending request to unhealty instances, but makes sure that already existing connections are handled correctly
What does “instance-monitoring Enabled=true” do on an auto scaling group
Enabling “detailed monitoring”, if “false” than normal monitoring is used
How can you connect on-prem servers with an ELB?
With direct connect or via a VPN
What is content-based routing?
Giving traffic to Target Gorups based on header information, such as the route /images or /forum
What is a Slow Start
New instances behind an ELB do not get as much traffic as older instances
ELB: What is a listener?
Handles requests based on conditions, such as ports or protocols.
An ELB has at least one listener
ELB: What is a target group?
A set of resources the LB directs traffic to. Sits behind the listener
ELB: What is a rule?
Defines rules on which target group the LB should direct traffic to, such as HTTP method or incoming IP
ELB: What is an ELB node?
For every AZ an ELB directs traffic to a node has to be set (this is done by selecting the AZs traffic wil be directed to)
ELB: What are the options to set a certificate to the LB?
1) Choose a certificate from ACM
2) Update a cert. from ACM
3) Choose a cert from IAM
4) Upload a cert from IAM
ELB: How is a request handles with HTTPS as the listener?
The encrypted request is terminated on the LB and then encrypted again using a different certificate
ELB: What is a “step scaling policy”?
policy that dictates different levels of scaling based on different utilization levels of a metric you’ve selected.
VPN: What are the parts of an AWS managed VPN?
Cloud: Virtual Private Gateway
Connection: Tunnel via IPSec
On-Premise: Customer Gateway
VPN: What is the Transit Gateway?
Central hub to connect multiple VPCs
VPN: What is the AWS VPN CloudHub?
Uses an Amazon VPC virtual private gateway with multiple customer gateways, each using unique BGP autonomous system numbers (ASNs). Your gateways advertise the appropriate routes (BGP prefixes) over their VPN connections.
What is AWS PrivateLink?
AWS PrivateLink provides private connectivity between VPCs and services hosted on AWS or on-premises, securely on the Amazon network. By providing a private endpoint to access your services, AWS PrivateLink ensures your traffic is not exposed to the public internet.
VPC: What makes a subnet public?
1) Internet Gateway - Subnet has a route (0.0.0.0/0) to the IG (igw-1234)
VPC: What allows the subnets to talk to each other?
The local route in the Routes Table.
Destination: CIDR Range of the VPC (10.0.0.0/16 e.g.)
Target: local
NACL: What are the configurable attributes of in/outbout rules?
Rule# (10 e.g.) Type (HTTP) Port (80) Source(in) /Destination(out) (0.0.0.0/0) Allow/Deny
What does stateful/stateless means for NACL/SG?
stateful: if inbound traffic is allowed, then the request can leave again
stateless: traffic can go in, but not out if not specified
What are the characteristics of a NAT Gateway (in terms of IPs, Subnet etc.)
It is located in a public subnet and has a public IP.
The private subnets that will use the NAT have a 0.0.0.0/0 destination route to the NAT Gateway (nat-012345)
The private subnets can only receive traffic after sending the request - the internet cannot directly talk to private subnets.
The Gateway is only accessible from the same AZ
How to connect from a Bastion Host to an instance in a private subnet?
SSH with your key to the Bastion.
Use SSH Agent Forwarding to ssh into the private instance
VPN: How is the route for a VPN connection to a Customer Gateway configured?
Destination: [CG] - 192.168.0.0/16 e.g.
Target: [VPG] - vgw-12345 e.g.
VPN: How are security groups configured for on premise networks?
The souce must reflect the IP / IP Range of the on premise network.
for example: HTTPS - 443 - 192.168.0.0/16