bind 8 scalability

[Jim Reid]

    >> I am currently looking to implement BIND 8 for NT and was
    >> wondering how many domains can I expect it to handle on a PII
    >> 333 with 512mb ram. I have a problem with BIND 4 where the
    >> server can't load more then 10,000 domains with the hardware
    >> spec I mentioned.

Recent versions of BIND8 can accommodate 2**24 zones, assuming the OS
lets the named process grow that big.

    >> What kind of hardware will I need to support 100K+ domains?

It depends on how much data (how many resource records) are in the
zones, how often they're queried and, if host-statistics are enabled,
where the queries come from. Your 333 Mhz PII should be good enough to
cope with around 3000 queries a second, subject to a few conditions:
	[1] the answers are already in the name server's cache
	[2] the name server cache is all physically resident in RAM
	[3] the OS doesn't run anything apart from named
	[4] the box runs a sensible OS - some flavour of BSD probably

A load of N-thousand queries a second is well into root name server
territory. Your server shouldn't be getting that volume of queries.
If it is you have lots of other problems to deal with: like not
having a good DNS architecture or zillions of broken (customer?) name
servers and resolvers.

As a rough rule of thumb, each resource record in the DNS occupies
~100 bytes. Every zone needs approx. 1K for a zoneinfo struct. From
these conservative estimates, you should have a good idea how much RAM
your name server(s) will need. The name server needs to keep all of
its cache in RAM - delays because of page faults are nasty! - so use
these numbers to figure out how much RAM is needed to load all your
DNS data.

    >> Can BIND 8 take advantage of multi processor system?

Not really. You need BIND9 for that. It is threaded, so if your
multiprocessor box has a reasonable threads implementation...  Mind
you, most name servers probably won't need to use extra CPUs unless
they're doing serious stuff with DNSSEC.