easy to understand definitions

[Kevin Darcy]

Sebastian Castro Avila wrote:

>On Wed, 23 Mar 2005 09:38:42 -0500, Bob Lockie <bjlockie at lockie.ca> wrote:
>
>  
>
>>I found the following definitions but I need definitions that are easier
>>to understand.
>>I do not have my Bind book available.
>>
>>#  refresh - How often the slave servers should check the serial number
>>on the master for changes.
>># retry - Amount of time a slave should wait before attempting another
>>"refresh" after a previous refresh has failed.
>>    
>>
>
>I agree with these first two definitions.
>
>  
>
>># expire - How long a slave should use it's DNS information without a
>>refresh from the master.
>>    
>>
>
>How long a slave can answer as an authoritative source without refreshing  
>with the master.
>When the "expire" timer ends, that server gives "SERVFAIL" for any  
>question regarding the domain.
>
>Reach that timer is BAD, so it's recommended to have a high value (2 to 4  
>weeks).
>
>
>  
>
>># minimum - How long a server should cache negative hits (e.g. no such
>>domain/host).
>>
>>    
>>
>
>Also, how long a server can keep the answer cached.
>
>If you have long values, any change you make will take longer to  
>propagate. If you choose a short value, your authoritative servers will  
>receive more queries.
>
You seem to be implying that SOA.MINIMUM affects the caching of positive 
responses. It does not. The TTL values on the individual RRs (or, more 
accurately, RRsets, since it is not legal for TTLs to differ within an 
RRset) controls caching of positive responses. SOA.MINIMUM only affects 
the caching of negative responses. See RFC 2308.

                                                                         
                        - Kevin