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Code Issues Releases Wiki Activity

Update logic stale refresh window in combination with client timeout

Matthijs Mekking 2021-01-21 16:13:37 +00:00
parent 4d5fc18bf1
commit bd440424fe
1 changed files with 2 additions and 4 deletions
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Serving-stale-data.md

@ -114,11 +114,9 @@ If `stale-answer-client-timeout` is set to 0, we prioritize stale positive answe
Now what happens if both `stale-refresh-time` and `stale-answer-client-timeout` are used? Now what happens if both `stale-refresh-time` and `stale-answer-client-timeout` are used?
First let us look at the case where `stale-answer-client-timeout` is 0. A request comes in, if there is a stale positive answer, we immediately return it and start an attempt to refresh the RRset. If there is no such cache entry, a regular lookup is started. First let us look at the case where `stale-answer-client-timeout` is 0. A request comes in, BIND checks if there is a stale cache entry. If there is one that for which `stale-refresh-time` is active, the stale answer is used in the response to the client. No attempt to refresh the entry is made, because the time window explicitly tells us not to do so. If no useful stale data was found, this query will now result in a server failure response.
In this lookup, it may be that there is a stale negative response which `stale-refresh-time` is active. In this case, the stale answer is used in the response to the client. No attempt to refresh the entry is made, because the time window explicitly tells us not to do so. If no stale data was found, this query will now result in a server failure response. If the `stale-refresh-time` window was inactive, the lookup will check if the stale entry in cache is a positive answer. If so, it can be used in the response to the client, and BIND starts an attempt to refresh the RRset. If the stale data is a negative cache entry, BIND will start resolving the query.
If the `stale-refresh-time` window was inactive, the lookup will trigger an attempt to resolve the query.
What if the `stale-answer-client-timeout` is set to a positive value? Then if a stale cache entry exists, and if the `stale-refresh-time` window was active for this RRset, the entry is immediately returned, without an attempt to resolve the query. What if the `stale-answer-client-timeout` is set to a positive value? Then if a stale cache entry exists, and if the `stale-refresh-time` window was active for this RRset, the entry is immediately returned, without an attempt to resolve the query.