Queries for www.tjhinc.com

[bsfinkel at anl.gov]

I wrote in part:

>> One of our users here complained about getting a SERVFAIL when
>> querying DNS for
>> 
>>      www.tjhinc.com.
>> 
>> I have done a number of queries (see below), and I do not understand
>> the results.  Here are the questions:
>> 
>> <<Items 1) and 2) omitted here.>>
>> 
>> 3) Sometimes I get a response that looks OK; there is one answer
>>    section and two authority sections with NS records.  Sometimes I
>>    get a response with one answer section (looks OK) and an
>>    authority section that has 13 NS records for "com."  Why?
>>
>> Here are the dig queries I ran:
>> 
>> titania% dig www.tjhinc.com
>> 
>> ; <<>> DiG 8.3 <<>> www.tjhinc.com 
>> ;; res options: init recurs defnam dnsrch
>> ;; got answer:
>> ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 2
>> ;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 2, ADDITIONAL: 0
>> ;; QUERY SECTION:
>> ;;      www.tjhinc.com, type = A, class = IN
>> 
>> ;; ANSWER SECTION:
>> www.tjhinc.com.         1D IN A         64.143.85.46
>> 
>> ;; AUTHORITY SECTION:
>> tjhinc.com.             1D IN NS        ns26b.sbc-webhosting.com.
>> tjhinc.com.             1D IN NS        ns26a.sbc-webhosting.com.
>> 
>> ;; Total query time: 54 msec
>> ;; FROM: titania to SERVER: default -- 146.139.254.5
>> ;; WHEN: Wed Aug 13 10:29:17 2008
>> ;; MSG SIZE  sent: 32  rcvd: 103
>> > titania% !!
>> dig www.tjhinc.com
>> 
>> ; <<>> DiG 8.3 <<>> www.tjhinc.com 
>> ;; res options: init recurs defnam dnsrch
>> ;; got answer:
>> ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 2
>> ;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 13, ADDITIONAL: 0
>> ;; QUERY SECTION:
>> ;;      www.tjhinc.com, type = A, class = IN
>> 
>> ;; ANSWER SECTION:
>> www.tjhinc.com.         23h59m52s IN A  64.143.85.46
>> 
>> ;; AUTHORITY SECTION:
>> com.                    1d23h59m59s IN NS  f.gtld-servers.net.
>> com.                    1d23h59m59s IN NS  j.gtld-servers.net.
>> com.                    1d23h59m59s IN NS  a.gtld-servers.net.
>> com.                    1d23h59m59s IN NS  d.gtld-servers.net.
>> com.                    1d23h59m59s IN NS  e.gtld-servers.net.
>> com.                    1d23h59m59s IN NS  g.gtld-servers.net.
>> com.                    1d23h59m59s IN NS  k.gtld-servers.net.
>> com.                    1d23h59m59s IN NS  l.gtld-servers.net.
>> com.                    1d23h59m59s IN NS  c.gtld-servers.net.
>> com.                    1d23h59m59s IN NS  m.gtld-servers.net.
>> com.                    1d23h59m59s IN NS  h.gtld-servers.net.
>> com.                    1d23h59m59s IN NS  i.gtld-servers.net.
>> com.                    1d23h59m59s IN NS  b.gtld-servers.net.
>> 
>> ;; Total query time: 2 msec
>> ;; FROM: titania to SERVER: default -- 146.139.254.5
>> ;; WHEN: Wed Aug 13 10:29:25 2008
>> ;; MSG SIZE  sent: 32  rcvd: 272
>> 
>> titania# !!
>> dig www.tjhinc.com
>> 
>> ; <<>> DiG 8.3 <<>> www.tjhinc.com 
>> ;; res options: init recurs defnam dnsrch
>> ;; got answer:
>> ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 2
>> ;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 2, ADDITIONAL: 0
>> ;; QUERY SECTION:
>> ;;      www.tjhinc.com, type = A, class = IN
>> 
>> ;; ANSWER SECTION:
>> www.tjhinc.com.         23h59m54s IN A  64.143.85.46
>> 
>> ;; AUTHORITY SECTION:
>> tjhinc.com.             23h59m54s IN NS  ns26b.sbc-webhosting.com.
>> tjhinc.com.             23h59m54s IN NS  ns26a.sbc-webhosting.com.
>> 
>> ;; Total query time: 1 msec
>> ;; FROM: titania to SERVER: default -- 146.139.254.5
>> ;; WHEN: Wed Aug 13 10:30:49 2008
>> ;; MSG SIZE  sent: 32  rcvd: 103
>> 
>> titania#

And Mark Andrews replied:
>
>	BIND 9.5 has a (least recently used) LRU cache with 1009
>	buckets.  You are seeing the LRU cleaning coming into effect.
>	There are some bucket related effects visible in the current
>	code in overmem situtions.
>
>	Increase max-cache-size from its default (32M) or reduce
>	DEFAULT_CACHE_NODE_LOCK_COUNT to reduce the bucket effects.
>
>lib/dns/rbtdb.c:
>#define DEFAULT_CACHE_NODE_LOCK_COUNT   1009    /*%< Should be prime. */

This is an answer to my questions 1) and 2), but is it an answer to
question 3)?  In the above three queries, I see

     a) a good query with a TTL of 1D and tjhinc.com authority,
     b) then a query with a slightly shorter than 1D TTL but with .com
             authority,
     c) then a good query with a slightly shorter than 1D TTL and
             tjhinc.com authority.

Another question arises - if the default max-cache-size is 32M
(and titania has 2G of memory), and the cache is supposedly full,
then why is the named_dumpdb file I created yesterday only 818340
bytes long?
----------------------------------------------------------------------
Barry S. Finkel
Computing and Information Systems Division
Argonne National Laboratory          Phone:    +1 (630) 252-7277
9700 South Cass Avenue               Facsimile:+1 (630) 252-4601
Building 222, Room D209              Internet: BSFinkel at anl.gov
Argonne, IL   60439-4828             IBMMAIL:  I1004994