Zone statistics, esp for tracking transfers, update status

It is important to know how your server is performing! Complex and large authoritative server setups - many secondaries, zones and data records - have a lot of plates spinning, or balls in the air (tasks running) and understanding how each of these tasks is behaving will help operators to know what is 'normal' and what is not.

This issue is to request additional counters in BIND, to provide metrics on various objects and activities. Here are some initial thoughts on what those might be:

1. Total current no. of zones. This is the sum of numbers of zones of all types (see below).
2. Current no. of primary zones, added by zone statements or dynamically using 'addzone'.
3. Current no. of secondary zones..
4. Current no. of forward zones..
5. Current no. of stub zones..
6. Current no. of static-stub zones..
7. Current no. of catalog zones (catz)
8. Current no. of rpz zones
9. No. of SOA queries currently in progress - similar in concept to the current no. of recursive clients. (this might exist already?
10. Histogram of times to resolve SOA zone refresh queries - similar to the query RTT buckets in named.stats.

• 0-0.999ms
• 1-4.999ms
• 5-9.999ms
• 10-19.999ms
• 20-49.999ms
• 50-99.999ms
• 100-499.99ms
• 500ms-infinity

11. No. of AXFRs currently in progress
12. No. of IXFRs currently in progress
13. Histogram of times XFRs have been in progress (the bucket sizes are a guess, not based on empirical data)

• 0-0.999s
• 1-4.999s
• 5-9.999s
• 10-19.999s
• 20-49.999s
• 50-99.999s
• 100-499.99s
• 500s-infinity