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R53 DNS summary

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abk edited this page Nov 26, 2019 · 2 revisions

Route53 (R53 - DNS service).

  • Zones are like DBs for the DNS
  • Zones contains records.
    • Will contain name server records
    • Will contain SOA records.
  • R53 supports 2 zones
    • Public zones
      • When you register “associatecats.com” - in the public domain.
      • They are globally accessible.
      • Public hosted is created when you register a domain with R53
      • A hosted zone has the same name as the domain it relates to e.g., linuxacademy.com will have hosted zone called linuxacademy.com
      • A public zone is accessible either internet based DNS clients or within any AWS VPCs
      • A hosted zone will have name servers - these are IP addresses you can give to domain operator, so R53 will become “authoritative’ for a domain
    • Private zones
      • Zones that live within private VPC.
      • They are ONLY accessible within VPCs
      • Private zones need “enableDnsHostnames” and “enableDnsSupport” needed on VPC
      • Not all R53 are supported. (Limits on health checks)
      • Split-view DNS is supported.
        • Split view DNS is using same zone name for public and private zones. Providing VPC resources with different records
        • Useful for testing, internal version of websites etc.
        • With split view, private is preferred - if no match public is used.

Healthchecks - Can be created within R53 and are used to influence Route53 routing decisions. There are 3 types of health checks

  1. Healthchekcs that monitor an endpoint : IP, hostname
  2. Health checks that monitor other health check (They are referred as calculated health checks)
  3. Health checks that monitor cloud watch alarms

18% or more is healthy, under that means unhealthy. Cccccclceggtdrugktkvbentbvnkiueukivnggdfuikf Cccccclceggtgflkdeifeflecvdrhvhjnvvdeljgcunc

How to register a domain using R53.

  1. Check the domain is available?
  2. Purchase the domain via a registrar
  3. Hosting the domain
  4. Records in the zone file.

Different type of records.

  • A record : Host to IPv4 address (IPv4 record)
  • AAAA record : Host to IPv6 address
  • C-name record : Used for aliases. Inside the domain you are in. IF you want to use outside, use FQDN.
  • MX record : Mail server for a given domain.
  • NS record : Used to set authoritative servers for subdomain. .com would have NS server for linuxacademy.com
  • TXT record : used for descriptive text. Used to verify domain ownership (gmail, office365 etc).
  • Alias record: An extension of CNAME. Behave like CNAME. They reference other things.

R53 health checks

What it provides?

  • When customer’s put a URL or domain name, if the hosted zones are set to amazon’s name servers,
R53 responds with an IP address.
  • DNS lookup address across the world - they are global.
  • Hosted zones in R53 give the IP addresses (IP address of EC2,S3 bucket, cloud front distribution, IP address of Load balancer etc).
They need not have single IP address associated with them.
  • Hosted zones
    • Public hosted zone
    • Private hosted zone.
  • Domain registration is possible.
  • Health checking
  • Routing policies are possible in R53.
    • Simple
    • Weighted (divide the traffic by %)
    • Latency - If you have multiple endpoints, return IP address of region closest.
    • Failover - If primary endpoint is unhealthy, return IP address of secondary endpoint
    • Geolocation - Based on country location / origination, return IP address

R53 Failover routing - How this works? For a hosted zone , record set - routing policy will be set to failover. Health check is enabled and primary is set to ALB and secondary can be set to S3.

ADAVNCED ROUTING POLICIES ####################### There are 2 MAIN Policies

  1. Simple routing policy
    • Simple starting point for DNS architecture
    • Single A record pointing 3 different server.
    • This is NOT load balancing.
    • Based on TTL value, the IP address is returned.
    • NO performance control or NO granular health check.
  2. Failover Routing policy
    • Give a primary, check for the health check
    • If primary health check fails, go for the secondary.
  • Weighted Routing policy.
    • Amount of traffic can be controlled that reaches specific resources.
    • Useful when testing new software or when resources are being added or removed from config that doesn’t use load balancer.
  • Latency Based Routing.
    • For every record you create for latency based routing, you specify the region.
    • Region is required latency based routing.
  • Geolocatiion based routing.

################## Key features

  1. Resolver
  2. Traffic flow
  3. Latency based routing
  4. Geo DNS
  5. Private DNS for amazon Vpc
  6. DNS failover
  7. Health checks and monitoring
  8. Domain registration
  9. CloudFront and S3 zone apex support
  10. Amazon ELB integration

DNS Concepts

  • Alias Record - A type of record that you can create to route traffic to AWS resources.
  • Hosted Zone - A container for records, which includes information about how to route traffic for a domain and all of its subdomains
  • Name servers - Servers in the DNS that help to translate domain names into the IP addresses
  • Record (DNS record) - An object in the hosted zone that you use to drive how you want to route traffic for domain or subdomain
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