Think - with -Tech: Route 53 - Records TTL (Time To Live)

Monday, June 9, 2025

Route 53 - Records TTL (Time To Live) | Overview & Hands-On.

Route 53 - Records TTL (Time To Live) - Overview & Hands-On.

In Amazon Route 53, the TTL (Time To Live) is an important DNS record setting that specifies how long (in seconds) a DNS resolver or cache should store a record before discarding it and querying the authoritative DNS server again (like Route 53) for updated information.

Why TTL Matters important

Caching Efficiency: Higher TTL values reduce DNS lookups by caching the result longer, improving performance and reducing load on your DNS servers.
Flexibility and Updates: Lower TTL values make DNS changes (like failovers, IP address changes) propagate faster.

TTL in Route 53 – Key Points

Attribute	Description
Defined per Record	TTL is set individually for each DNS record in Route 53.
Value Type	Integer, in seconds. Common values: 300, 600, 3600, etc.
Minimum TTL	No enforced minimum, but very low TTLs (e.g., <60s) may increase DNS traffic.
Effect on Caching	Shorter TTL = faster DNS propagation, but higher load.
Default Behavior	twech must specify TTL when creating records (some wizards suggest 300 seconds by default).

Example

If twtech creates an A record like:

# text

Name: www.web.twtechapp.com

Type: A

Value: 172.22.33.44

TTL: 300

That means any DNS resolver that looks up www.example.com will cache the result for 5 minutes (300 seconds) before re-querying Route 53.

twtech Best Practices

Use low TTLs (e.g., 60–300s) during:

Website migrations
IP changes
Failover configuration

Use high TTLs (e.g., 3600–86400s) for:

Stable, rarely changing records

* Reducing DNS costs and latency

use case:

To avoid querying the records too often.
TTL is a value in seconds that indicates how long a DNS resolver (like twtech ISP) cache the DNS information before refreshing it from the authoritative nameserver.
TTL can be also be configured using the command-line tools: like dig or nslookup.

Project: Hands-on

How twtech creates a record set while setting value for : TTL

Step-1:

Select the hosted zone to create the : A records

Create the: A records

Step-2:

Assign a name: springapp.twtechapp.com

Value (PubIPv address of an instance): 18.220.xxx.154

Set the TTL to: 120 seconds

Create the A record for: springapp.twtechapp.com

Step-3:

twtech uses the UI (browser) to access the A record created:

NB:

Sometime the browsers may not be compatible with the A records: springapp.twtechapp.com
Firefox : successfully queried the application with the record set

However, google chrome won’t query data from the application using the same A record: springapp.twtechapp.com

twtech recommendation: if a browser is not compactible, try another browser.

Step-4:

twtech uses CloudShell to run nslookup for: A records

Step-5:

Install command bind-utilits utility:

sudo yum install bind-utils -y

Step-5:
twtech runs the nslookup command again to search for rocord set created: springapp.twtechapp.com

# Command: nslookup springapp.twtechapp.com

Server: 127.0.0.11

Address: 127.0.0.11#53

Non-authoritative answer:

Name: springapp.twtechapp.com

Address: 18.220.xxx.154

Step-5:

twech uses the dig command to get more detail about the record set : dig springapp.twtechapp.com

Step-6:

twtech edit the A record value (PubIPv4 address) to route traffic to an instance in another region:
From Ohio to N. California.

From:

To: save changes

NB:

twtech makes sure the record set name already used in the account is not repeated

Step-7:

twtech verifies that the A record edited and directed to the application N. California is reachable (accessisble from the public) : twetechweb.twtechapp.com
Successfully, traffic is now routed to the instance in us-west-1 (N.California) by simply: editing an existing A records.

NB:

In order for twtech to query data from this instance, it must take: 120 sec initially set for TTL, for new data to be queried from the edited A record.

From: