4 ms·

But those are no valid use cases which was my question. So there are no valid use cases at all?

hiq 6y ago
> Administrators wanting their changes to be applied immediately, because it may require less planning work. Why is this not valid?
- JimWestergren 6y ago
  But 5 minutes should be fine? It surprised me that so many has 1 second or 20 second TTL.
  - samvher 6y ago
    If I need to get a web service up and I can save 4 minutes by setting a low TTL when I configure my DNS record why wouldn't I?
    - gertrunde 6y ago
      Because you're pushing the cost on to someone else. If your DNS hosting provider charged you per query (some do, especially when adding features like health checks & load balancing), then it might make a big difference.
- fomine3 6y ago
  Valid migration plan should be able to handle it without very short TTL.
prophesi 6y ago
A low DNS TTL for testing purposes is a valid use case.
- majewsky 6y ago
  This is about production systems of large enterprises. ... Please tell me you're not testing in production.
JimWestergren 6y ago
Found an earlier HN discussion about this question from November 2019: https://news.ycombinator.com/item?id=21437160 https://news.ycombinator.com/item?id=21437160
gwittel 6y ago
The major cases revolve around failure recovery, and traffic distribution. A 5 minute outage is not acceptable in many industries or at scale. If a load balancer or DC fails we need to ensure traffic moves away fast. Similarly if you want to take a system out for maintenance or perform migrations.
- marcosdumay 6y ago
  > A 5 minute outage is not acceptable in many industries or at scale. Well, if that's the case, you better have your redundant systems on your normal DNS entries, because there is no chance you will distribute new entries over the internet in 5 minutes, whatever value you specify at the TTL.
  - toast0 6y ago
    There are tons of things that don't follow TTLs, but a large majority of normal people traffic does. Easily 90% of new connections will move following the TTL. Of course, some traffic got a DNS result once in 2003 and is going to use that forever. If it's important traffic, you can trace it and follow up with them. If not, you do the best you can and let the rest go.

hiq 6y ago

> Administrators wanting their changes to be applied immediately, because it may require less planning work. Why is this not valid?

JimWestergren 6y ago
But 5 minutes should be fine? It surprised me that so many has 1 second or 20 second TTL.
- samvher 6y ago
  If I need to get a web service up and I can save 4 minutes by setting a low TTL when I configure my DNS record why wouldn't I?
  - gertrunde 6y ago
    Because you're pushing the cost on to someone else. If your DNS hosting provider charged you per query (some do, especially when adding features like health checks & load balancing), then it might make a big difference.
fomine3 6y ago
Valid migration plan should be able to handle it without very short TTL.

prophesi 6y ago

A low DNS TTL for testing purposes is a valid use case.

majewsky 6y ago
This is about production systems of large enterprises. ... Please tell me you're not testing in production.

JimWestergren 6y ago

Found an earlier HN discussion about this question from November 2019: https://news.ycombinator.com/item?id=21437160 https://news.ycombinator.com/item?id=21437160

gwittel 6y ago

The major cases revolve around failure recovery, and traffic distribution. A 5 minute outage is not acceptable in many industries or at scale. If a load balancer or DC fails we need to ensure traffic moves away fast. Similarly if you want to take a system out for maintenance or perform migrations.

marcosdumay 6y ago
> A 5 minute outage is not acceptable in many industries or at scale. Well, if that's the case, you better have your redundant systems on your normal DNS entries, because there is no chance you will distribute new entries over the internet in 5 minutes, whatever value you specify at the TTL.
- toast0 6y ago
  There are tons of things that don't follow TTLs, but a large majority of normal people traffic does. Easily 90% of new connections will move following the TTL. Of course, some traffic got a DNS result once in 2003 and is going to use that forever. If it's important traffic, you can trace it and follow up with them. If not, you do the best you can and let the rest go.