7_Route53 Flashcards
DNS 101
- ELB’s do not have pre-defined IPv4 addresses, you resolve to them using a DNS name
- Alias and CNAMES are similar in that you can map one DNS name (www.example.com) to another ‘target’ DNS name (elb1234.elb.amazonaws.com)
- Key difference between Alias and CNAMES: A CNAME can’t be used for naked domain names (zone apex). You can’t have a CNAME for http://patin.com (but you can for http://www.patin.com), it must be either an A record or an Alias.
- Given the choice, always choose an Alias record over a CNAME
DNS 101
- ELB’s do not have pre-defined IPv4 addresses, you resolve to them using a DNS name
- Alias and CNAMES are similar in that you can map one DNS name (www.example.com) to another ‘target’ DNS name (elb1234.elb.amazonaws.com)
- Key difference between Alias and CNAMES: A CNAME can’t be used for naked domain names (zone apex). You can’t have a CNAME for http://patin.com (but you can for http://www.patin.com), it must be either an A record or an Alias.
Common DNS Types
- SOA Records
- NS Records
- A Records
- CNAMES
- MX Records
- PTR Records
Alias Records
Alias resource record sets can save you time because Amazon Route 53 automatically recognizes changes in the record sets that the alias resource record set refers to.
For example, suppose an alias resource record set for example.com points to an ELB load balancer at lb1-1234.us-east-1.elb.amazonaws.com. If the IP address of the load balancer changes, Amazon Route 53 will automatically reflect those changes in DNS answers for example.com without any changes to the hosted zone that contains resource record sets for example.com
Alias Records
Alias resource record sets can save you time because Amazon Route 53 automatically recognizes changes in the record sets that the alias resource record set refers to.
For example, suppose an alias resource record set for example.com points to an ELB load balancer at lb1-1234.us-east-1.elb.amazonaws.com. If the IP address of the load balancer changes, Amazon Route 53 will automatically reflect those changes in DNS answers for example.com without any changes to the hosted zone that contains resource record sets for example.com
Route53 - Routing Policies
- Simple
- Weighted
- Latency
- Failover
- Geolocation
- Geoproximity (Traffic flow only)
- Mutlivalue Answer
Route53 - Routing Policies
- Simple
- Weighted
- Latency
- Failover
- Geolocation
Routing Policies - Simple
If you choose the simple routing policy you can only have one record with multiple IP addresses. If you specify multiple values in a record, Route53 returns all values to the user in a random order.
Routing Policies - Simple
This is the default routing policy when you create a new record set. This is most commonly used when you have a single resource that performs a given function for your domain, for example, one web server that serves content for the http://example.com
Routing Policies - Weighted
Weighted Routing Policies let you split your traffic based on different weights assigned.
For example you can set 20% of your traffic to go to US-EAST-1 and 80% to go to EU-WEST-1
Health Checks:
- You can set health checks on individual record sets.
- If a records set fails a health check it will be remove from Route53 until it passes the health check
- You can set SNS notifications to alert you if a health check is failed
Routing Policies - Weighted
Weighted Routing Policies let you split your traffic based on different weights assigned.
For example you can set 10% of your traffic to go to US-EAST-1 and 90% to go to EU-WEST-1
Routing Policies - Latency
Latency based routing allows you to route your traffic based on the lowest network latency for your end user (i.e. which region will give them the fastest response time).
To use latency-based routing you create a latency resource record set for the Amazon EC2 (or ELB) resource in each region that hosts your website. When Amazon Route 53 receives a query for your site, it selects the latency resource record for the region that gives the user the lowest latency. Route53 then responds with the value associated with that resource record set.
Routing Policies - Latency
Latency based routing allows you to route your traffic based on the lowest network latency for your end user (i.e. which region will give them the fastest response time).
To use latency-based routing you create a latency resource record set for the Amazon EC2 (or ELB) resource in each region that hosts your website. When Amazon Route 53 receives a query for your site, it selects the latency resource record for the region that gives the user the lowest latency. Route53 then responds with the value associated with that resource record set.
Routing Policies - Failover
Failover routing policies are used when you want to create an active/passive setup. For example you may want your primary site to be in EU-WEST-2 and your secondary DR site in AP-SOUTHEAST-2.
Route53 will monitor the health of your primary site using a healthcheck.
A healthcheck monitors the health of your end points.
Routing Policies - Failover
Failover routing policies are used when you want to create an active/passive setup. For example you may want your primary site to be in EU-WEST-2 and your secondary DR site in AP-SOUTHEAST-2.
Route53 will monitor the health of your primary site using a healthcheck.
A healthcheck monitors the health of your end points.
Routing Policies - Geolocation
Geolocation routing lets you choose where your traffic will be sent based on the geographic location of your users (i.e. the location from which DNS queries originate).
For example, you might want all queries from Europe to be routed to a fleet of EC2 instances that are specifically configured for your European customers. These servers may have the local language of your European customers and all prices are displayed in Euros.
Routing Policies - Geolocation
Geolocation routing lets you choose where your traffic will be sent based on the geographic location of your users (i.e. the location from which DNS queries originate).
For example, you might want all queries from Europe to be routed to a fleet of EC2 instances that are specifically configured for your European customers. These servers may have the local language of your European customers and all prices are displayed in Euros.
Routing Policies - Geoproximity
Geoproximity routing lets Amazon Route53 route traffic to your resources based on the geographic location of your users and resources. You can also optionally choose to route more traffic or less to a resource by specifying a value, known as bias. A bias expands or shrinks the size of the geographic region from which traffic is routed a resource.
To use geoproximity routing, you must use Route 53 Traffic Flow
Routing Policies - Multivalue Answer
Multivalue Answer routing lets you configure Amazon Route53 to return multiple values, such as IP addresses for your web servers, in response to DNS queries. You can speficy multiple values for almost any record, but multivalue answer routing also lets you check the health of each resource, so Route53 returns only values for healthy resources.
This is similar to the simple routing however it allows you to put health checks on each record set.
Compare Elastic Load Balancing and Amazon Route 53
Compare Elastic Load Balancing and Amazon Route 53
What kinds of Records does Amazon Route 53 support?
- Many standard DNS records are supported
- Alias records provide an Amazon Route 53-specific extension to DNS functionality. Instead of an IP address or domain name:
- Amazon CloudFront distribution
- Elastic Load Balacing load balancer
- Amazon S3 bucket configured as a static website
- Amazon Route 53 resource record set in the same hosted zone
What kinds of Records does Amazon Route 53 support?
- Many standard DNS records are supported
- Alias records provide an Amazon Route 53-specific extension to DNS functionality. Instead of an IP address or domain name:
- Amazon CloudFront distribution
- Elastic Load Balacing load balancer
- Amazon S3 bucket configured as a static website
- Amazon Route 53 resource record set in the same hosted zone
