Route 53

Created : March 31, 2020

This note was taken while learning AWS on Udemy.

Route 53

: scalable cloud DNS web service - register new domains, transfer existing domains

DNS (Domain Name System)

  • convert human friendly domain names into IP address
  • IP addresses are used by computers to identify each other on the network

    • come in 2 different forms - IPv4 and IPv6
  • .com.au

    • au : top-level domain
    • com : second level domain name
  • ELBs never have pre-defined IPv4 addresses

    • always resolve to them using DNS name
  • Alias Record : virtual host record type which is used to point one domain name to another one

    • in exam, always choose Alias Record over CNAME
  • IPv4 vs IPv6

    • IPv4

      • 32bit - 4B different address - is running out
    • IPv6

      • 128bit

Routing Policies

When you create a record, you choose a routing policy, which determines how Route 53 responds to queries

1. Simple routing

  • only have one record with multiple IP addresses
  • if you specify multiple values in a record, Route 53 returns all values to the user in a random order.
  • send 1st traffic to 1st record, 2nd traffic to 2nd record
  • cannot use health check

2. Weighted routing

  • split traffic based on different weights assigned
  • e.g. set 10% of traffic to go to US-East-1 and 90% to go to EU-West-1

3. Latency routing

  • when you want to create an active/passive set up
  • primary(active) site to be in EU-West-2 and secondary(passive) DR site in CA-Central-1
  • when you detect a failure in primary site, send traffic to secondary instead

4. Geolocation routing

  • choose where traffic will be sent based on the geographic location of users (location from which DNS queries originate)
  • send European users to EU-West-1, US users to US-East-1
  • e.g. all queries from Europe

    • routed to a fleet of EC2 instances that are specifically configured for European customers
    • such as local language and currency in Euros

5. Multivalue Answer routing

  • configure Route 53 to return multiple values
  • like IP addresses for web servers, in response to DNS queries
  • let you check health of each resource,

    • Route 53 returns only values for healthy resources
  • if 1st one is unhealthy, send to 2nd
  • similar to simple routing, but this one can use health check

< Health Checks >

  • can set health checks on individual record sets
  • if a record set fails a health check, it'll be removed from Route53 until it passes health check.
  • can set SNS notifications to alert you if failed