88
edits
Networking/DNS/Host resolver: Difference between revisions
Jump to navigation
Jump to search
m
→Access to TTL
(Placeholder for DNS host resolver investigation Q1 2012) |
m (→Access to TTL) |
||
| Line 6: | Line 6: | ||
=== Access to TTL === | === Access to TTL === | ||
From Patrick: "Right now our ttl is generally too short at 3 minutes - leading to the potential performance problem of having to block on a lookup of an expired entry... We use the conservative number because some actual TTLs are smaller than that. Generally stuff associated with global load balancers. None of that is expected to work precisely, so I'm ok with 3 minutes but I'd want to think hard before making it a lot larger than that carte blanche. real TTLs mean we don't have to do it carte blanche." | From Patrick: "Right now our ttl is generally too short at 3 minutes - leading to the potential performance problem of having to block on a lookup of an expired entry... We use the conservative number because some actual TTLs are smaller than that. Generally stuff associated with global load balancers. None of that is expected to work precisely, so I'm ok with 3 minutes but I'd want to think hard before making it a lot larger than that carte blanche. real TTLs mean we don't have to do it carte blanche." | ||
Note: According to [http://support.microsoft.com/kb/318803 Microsoft], Windows XP considers TTL in its OS cache. The article suggests that the lesser of the real TTL or a max TTL value is used for the time to expiration in the OS's DNS cache. The max TTL value defaults to 1 day. Firefox makes use of this cache, so TTL may already be covered indirectly in the Windows XP case. | |||
=== Concurrency without multiple threads === | === Concurrency without multiple threads === | ||