What is DNS TTL
DNS TTL stands for Time to Live. It is a field in a DNS record that specifies how long the record should be cached by DNS resolvers. The TTL is measured in seconds.
When a DNS resolver queries an authoritative DNS server for a record, the authoritative server will return the record along with the TTL. The resolver will then cache the record for the specified TTL period. If the resolver needs to query the record again before the TTL period expires, it will use the cached record instead of querying the authoritative server again.
The TTL is important for two reasons.
First, it helps to improve the performance of DNS queries. When a resolver caches a record, it does not have to query the authoritative server again for the same record. This can save time and resources, especially for frequently accessed records.
Second, the TTL helps to prevent DNS cache poisoning.
DNS cache poisoning is a type of attack where an attacker injects a malicious record into a DNS resolver's cache. If the malicious record has a long TTL, it can remain in the cache for a long time, potentially affecting many users. By setting a short TTL, resolvers can quickly invalidate malicious records and prevent them from affecting users.
The default TTL for most DNS records is 3600 seconds (1 hour) though has 14400 seconds (4 hours) for most besides NS (nameserver).
However, you can set the TTL to any value you want.
The best TTL value for a particular record will depend on a number of factors, such as the frequency of changes to the record, the importance of the record, and the performance requirements of your network.
Here are some general guidelines for setting DNS TTL values:
- For records that change frequently, such as A records for web servers, you should use a short TTL, such as 300 seconds (5 minutes). This will ensure that users always get the most up-to-date information.
- For records that change less frequently, such as MX records for email servers, you can use a longer TTL, such as 600 seconds (10 minutes). This will reduce the number of DNS queries that need to be made, which can improve performance.
- For records that are very important, such as NS records for your domain name, you should use a very long TTL, such as 86400 seconds (24 hours). This will help to prevent DNS cache poisoning attacks.
Ultimately, the best way to determine the right TTL value for a particular record is to experiment and see what works best for your needs.
How To Configure Default TTL in WHM
To modify the default Time-to-Live (TTL) value for newly created cPanel accounts' DNS zones, you need to edit the DNS Zone Template within WHM. This affects how long DNS information is cached by resolving name servers.
Answer
Follow these steps to make the change:
Navigate to WHM's [Home »DNS Functions »Edit Zone Templates].
Select the correct zone template to change.
The template for "standardvirtualftp" is commonly edited as it is the template for domains using the server's main shared IP.
Find the main TTL value in the third line of the template:
; cPanel %cpversion%
; Zone file for %domain%
$TTL %ttl%
Replace "%TTL%"
with the correct value you'd like to use.
For example: $TTL 600
Save the changes.
After performing these steps, newly created cPanel accounts will use the new TTL for their DNS entries.
This change allows you to control the caching behavior for DNS information, which can have implications for performance and updates to DNS records.
