Configuring DNS zones and conditional forwarding

Can you explain what DNS zones are and their significance in AWS?

DNS zones act as containers for DNS settings and records for a single domain or a portion of a domain within AWS’ Route 53 service. They are significant because they enable the management of domain names and the corresponding IP addresses that the domain’s resources should resolve to, thereby dictating how traffic is routed for a domain.

How do you create a hosted zone in AWS Route 53, and what types are there?

To create a hosted zone in AWS Route 53, you need to go to the Route 53 dashboard, select “Hosted zones,” and click “Create hosted zone.” You then provide the domain name and choose the type of zone: public (for domains accessible on the internet) or private (for domains accessible only within one or more VPCs).

What is conditional DNS forwarding, and when would you use it on AWS?

Conditional DNS forwarding is a configuration that specifies DNS queries for a particular domain (or set of domains) to be forwarded to a specific DNS server, instead of using the default DNS resolution route. In AWS, this can be used when resolving domain names that are located within a different VPC, on-premises data center, or another cloud provider that AWS Route 53 wouldn’t normally be able to resolve.

Describe the steps required to set up conditional forwarding in AWS Route

To set up conditional forwarding in AWS Route 53, you need to:

• Create a Resolver rule that specifies the domain names for the DNS queries to match.
• Set the IP addresses of the DNS service to forward the queries to.
• Associate the rule with VPC(s) where you want the rule to take effect.

What record sets do you need to configure for a new domain in a DNS hosted zone?

For a new domain in a DNS hosted zone, at a minimum, you need to configure:

• An SOA (Start of Authority) record, which is created automatically with the zone.
• An NS (Name Server) record, also created automatically, that lists the authoritative name servers for the domain.
• An A (Address) record pointing the domain name to an IPv4 address or AAAA for IPv
• Optionally, other records such as CNAME (Canonical Name), MX (Mail Exchange), TXT, and SRV as needed by the domain’s services.

How can you migrate DNS services for an existing domain to AWS Route 53?

To migrate DNS services for an existing domain to AWS Route 53:

• Create a new hosted zone for the domain.
• Recreate all DNS record sets from the old DNS provider into the new hosted zone.
• Update the domain’s registrar with the name servers of the newly created hosted zone in Route
• Monitor for propagation and ensure services remain operational before decommissioning the old DNS service.

In what scenarios might you need to use both Route 53 and AWS Directory Service with conditional DNS forwarding?

You might need to use Route 53 along with AWS Directory Service in scenarios where you want to integrate AWS resources with an on-premises Active Directory or when using AWS Managed Microsoft AD. Conditional DNS forwarding would be used to resolve domain requests between resources in AWS and the on-premises environment or between VPCs connected to different directories.

What is a split-view (split-horizon) DNS, and how would you implement it in AWS?

Split-view DNS is a mechanism to provide different DNS responses based on the source of the DNS query, commonly used to give internal users (within an intranet or private VPC) different IP addresses than external users (on the public internet). In AWS, this is implemented by setting up private hosted zones for internal resources, and public hosted zones for external resources, providing access controls and rules that return different responses based on the query origin.

How does AWS Route 53 handle DNS failover, and can it be integrated with health checks?

AWS Route 53 can be configured to handle DNS failover by routing traffic to healthy endpoints. It can be integrated with health checks that monitor the health of your endpoints. If an endpoint fails a health check, Route 53 can automatically route traffic away from the failed endpoint to a healthy one, thus providing high availability and fault tolerance for your applications.

When configuring DNS records, what is the difference between an Alias record and a CNAME record in AWS Route 53?

An Alias record in AWS Route 53 is a Route 53-specific feature that lets you map resource record sets in your hosted zone to AWS resources such as Elastic Load Balancers, CloudFront distributions, or S3 buckets that are configured as websites. Alias records provide a similar function to CNAME records but without the limitations: they can be used for naked domain names (e.g., example.com without the ‘www’), and they are evaluated for routing policies such as Failover or Latency. Unlike CNAME records, Alias records are also free of charge because the DNS queries resolve to AWS resources.

What is the difference between forward and reverse DNS lookup, and how does AWS Route 53 support them?

Forward DNS lookup is the process of converting a domain name into a corresponding IP address, while reverse DNS lookup is the conversion of an IP address into its associated domain name. AWS Route 53 supports forward DNS lookups by managing DNS records for domain names. For reverse DNS lookup, AWS supports configuring PTR records (Pointer records), but only for Elastic IP addresses or specific AWS resources that require reverse DNS for functionalities like email server verification.

Can you explain how to configure Route 53 to handle traffic for multiple domains, possibly across different AWS accounts?

To configure Route 53 to handle traffic for multiple domains across different AWS accounts, you would:

• Create hosted zones for each domain within the respective AWS accounts.
• Set up appropriate record sets for the resources in each hosted zone.
• If cross-account access is needed, use IAM (Identity and Access Management) policies to delegate permissions to users or services in different accounts.
• For a unified view, consider using AWS Resource Access Manager (RAM) to share the hosted zones across accounts, allowing central management of DNS records.