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15.2 Checking the Cache
As we've said earlier, you can check
the contents of your name server's cache with the
DNS console. This can come in handy if you suspect that your name
server has cached bad or out-of-date data from another server. To
inspect a server's cache, click the plus sign to the
left of the name of the server in the DNS console's
left pane. You'll see a folder named Cached Lookups. Either click on the plus sign
to the left of it or double-click the folder icon or the label to
expand the next level, then do the same on the label . (root). This shows you the top-level domains
for which your name server has cached data. Expand your way to the
domain name to which the cached data you're looking
for is attached. In Figure 15-1,
we've clicked our way down to
acmebw.com to look for cached data.
Figure 15-1. NS and A records for acmebw.com in the cache
As you can see in the right pane, our name server has cached seven NS
records and one A record for acmebw.com. If we
double-clicked net and then
acmebw, we could find the cached
addresses of these name servers, too.If you'd like to see the TTL on the cached data,
double-click on a record in the right pane. Provided the DNS console
is in advanced view mode (select View
Advanced), the resulting window shows therecord's TTL. For example, in Figure 15-2, we've double-clicked the
acmebw.com A record.
Figure 15-2. The TTL on a cached record
Be sure to refresh the DNS console with Action
Refresh or F5before checking the TTL, or the TTL you see may be bigger than the
current TTL.If you right-clicked the record, you may have noticed a Delete Record selection. Now
there's something you can't do in
BIND. Using the DNS console, you can actually delete cached data
record by record! If you know that some records in your name
server's cache are out of date, you can delete them
and let your name server pick up updated records from an
authoritative name server.
