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Suppose registrar's Names server goes down, then my website will not available. For sure they have a second name server. But I will not rely on that one (in case of an serious outage at the registrar)

I'm not able to configure a second name server outsite of the registrar.

So I was thinking: will increase the TTL to let's say 24 hours decrease the dependency of the availability of the name server?

So, if the outage is less than 24 hours, and the TTL is 24 hours, will my website be available despite the name server outage?

Cœur
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luvTweb
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  • This seems like a good question on the wrong site. Perhaps http://webmasters.stackexchange.com/ is the right place, or http://serverfault.stackexchange.com - have a look around. Chances of a good answer go up by addressing the right audience. – Floris Jun 03 '14 at 19:12

1 Answers1

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How requests to your site actually work:

  1. Your site is just an IP
  2. Your site has a domain name - a sugar which helps users to remember it
  3. When a program wants to access your site by domain name - it does a system call to OS: gethostbyname which returns an IP address of the site and then program continues.
  4. OS has a DNS cache - which means that it queries nameservers only when cache is expired.
  5. OS queries not nameservers of your site, but nameservers which are preconfigured by provider (if user didnt override the setting).
  6. Provider checks its cache and if it is expired/not exists - queries root servers
  7. Root servers check their cache and if if it is expired/not exists - query domain zone servers
  8. Domain zone servers contain info about the site (because it is registered in them) and if site IP is not cached in them - they query its nameserver and get the IP

Soo.. in all steps between 3-8 your site ip address is getting cached and it all depends on cache ttl on all those servers and when the site was accessed last time on them.

To answer your question - TTL of 24h increases availability but not significantly.

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Vitaly Dyatlov
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