Server1 doesn't necessarily believe the glue records from the response
to the previous query since Server3 is not, as far as it knows,
authoritative for anything under .org. The data isn't very "credible".
So Server1 goes back up to the root server (Server2) to get an
"independent" resolution of that name.
- Kevin
Nobumichi Ozoe wrote:
>Hi,
>
>Now I am testing the recursive PTR query of BIND 9.3.1.
>
>The DNS Client1 request for PTR RRs for 10.1.168.192.IN-ADDR.ARPA to DNS Server1.
>
> % dig @192.168.0.10 10.1.168.192.IN-ADDR.ARPA. -t PTR
>
>DNS Server1 receved standard query from DNS Client1, and transmits recursive query.
>It's sequence flow are described as following.
>
>When DNS Server1 received No. 5 packet, I expect that DNS Server1 sends
>QNAME=10.1.168.192.IN-ADDR.ARPA, QTYPE=PTR query to DNS Server4 (No. 6 sequence).
>However DNS Server1 sends QNAME=NS4.example.org, QTYPE=A query to DNS Server2.
>
>Q. Why DNS Server1 doesn't send QNAME=10.1.168.192.IN-ADDR.ARPA, QTYPE=PTR query to
> DNS Server4 as authority of 168.192.IN-ADDR.ARPA?
>
>Topology
>---------
>
> IN-ADDR.ARPA domain 192.IN-ADDR.ARPA domain 168.192.IN-ADDR.ARPA domain
> DNS Server2 DNS Server3 DNS Server4
> |A.ROOT.NET |NS3.example.net |NS4.example.org
> |192.168.1.20 |192.168.1.30 |192.168.1.40
> | | |
>Net-y --+--------+---------------+------------+-----------+------- 192.168.1/24
> | |
> | |1.168.192.IN-ADDR.ARPA domain
> Router (TN) DNS Server5
> | NS5.example.org
> |192.168.0.1 192.168.1.50
> |
>Net-z --+--------+-----------------+-------- 192.168.0/24
> | |
> | |
> DNS Server1 (NUT) DNS Client1 (TN)
> NS1.example.com
> 192.168.0.10 192.168.0.20
>
>
>Configuration
>--------------
>
>named configuration is:
>
>options {
> directory "/etc/namedb";
> pid-file "/var/run/named/pid";
> dump-file "/var/dump/named_dump.db";
> statistics-file "/var/stats/named.stats";
> listen-on { any;};
> listen-on-v6 { any;};
> notify no;
> recursion yes;
> request-ixfr no;
> provide-ixfr no;
>};
>zone "." {
> type hint;
> file "named.root";
>};
>zone "example.com" {
> type master;
> allow-query {any;};
> allow-transfer {any;};
> file "master/example.com";
>};
>
>
>Zone files
>----------
>
>DNS Server1 is a name server for the example.com.
>The zone data for the example.com domain is:
>
>$TTL 86400 ; TTL of 1 day
>@ IN SOA NS1.example.com. root.example.com. (
> 2005081600 ; serial
> 3600 ; refresh every 1 hr
> 900 ; retry every 15 min
> 604800 ; expire after a week
> 3600 ; Minimum TTL of a 1 hr
>)
>;
> IN NS NS1.example.com.
>NS1 IN A 192.168.0.10
>
>
>DNS Server2 is a name server for the root. Root server list on DNS Server1 is:
>
>. 3600000 IN NS A.ROOT.NET.
>A.ROOT.NET. 3600000 A 192.168.1.20
>
>Sequence flow.
>--------------
> * TN: Tester node
> * NUT: Node under test
> <--------------- TN ---------------------------->
> DNS Client1 (TN) DNS Server1 (NUT) DNS Server2 DNS Server3 DNS Server4 DNS Server5
> | | | | | |
> |----------------------------->| | | | |
> | 1. Send standard query | | | | |
> | QNAME | | | | |
> | =10.1.168.192.IN-ADDR.ARPA | | | | |
> | QTYPE=PTR | | | | |
> | |-------------------------------->| | | |
> | | 2. Recv standard query | | | |
> | | QNAME | | | |
> | | =10.1.168.192.IN-ADDR.ARPA | | | |
> | | QTYPE=PTR | | | |
> | | | | | |
> | |<--------------------------------| | | |
> | | 3. Send standard query response | | | |
> | | QNAME | | | |
> | | =10.1.168.192.IN-ADDR.ARPA | | | |
> | | QTYPE=PTR | | | |
> | | AUTHORITY Name | | | |
> | | =192.IN-ADDR.ARPA | | | |
> | | AUTHORITY NSDNAME | | | |
> | | =NS3.example.net | | | |
> | | ADDITIONAL Name | | | |
> | | =NS3.example.net | | | |
> | | ADDITIONAL Address | | | |
> | | =192.168.1.30 | | | |
> | | | | | |
> | | v | | |
> | | | | |
> | |-------------------------------------------->| | |
> | | 4. Recv standard query | | |
> | | QNAME | | |
> | | =10.1.168.192.IN-ADDR.ARPA | | |
> | | QTYPE=PTR | | |
> | | | | |
> | |<--------------------------------------------| | |
> | | 5. Send standard query response | | |
> | | QNAME | | |
> | | =10.1.168.192.IN-ADDR.ARPA | | |
> | | QTYPE=PTR | | |
> | | AUTHORITY Name | | |
> | | = 168.192.IN-ADDR.ARPA | | |
> | | AUTHORITY NSDNAME | | |
> | | = NS4.example.org | | |
> | | ADDITIONAL Name | | |
> | | = NS4.example.org | | |
> | | ADDITIONAL Address | | |
> | | = 192.168.1.40 | | |
> | | | | |
> | | v | |
> | | | |
> | |-------------------------------------------------------->| |
> | | 6. Send standard query | |
> | | QNAME | |
> | | =10.1.168.192.IN-ADDR.ARPA | |
> | | QTYPE=PTR | |
> | | | |
> | |<--------------------------------------------------------| |
> | | 7. Send standard query response| |
> | | QNAME | |
> | | =10.1.168.192.IN-ADDR.ARPA | |
> | | QTYPE=PTR | |
> | | AUTHORITY Name | |
> | | = 1.168.192.IN-ADDR.ARPA | |
> | | AUTHORITY NSDNAME | |
> | | = NS5.example.org | |
> | | ADDITIONAL Name | |
> | | = NS5.example.org | |
> | | ADDITIONAL Address | |
> | | = 192.168.1.50 | |
> | | | |
> | | v |
> | | |
> | |-------------------------------------------------------------------->|
> | | 8. Send standard query |
> | | QNAME |
> | | =10.1.168.192.IN-ADDR.ARPA |
> | | QTYPE=PTR |
> | | |
> | |<--------------------------------------------------------------------|
> | | 9. Send standard query response |
> | | QNAME |
> | | =10.1.168.192.IN-ADDR.ARPA |
> | | QTYPE=PTR |
> | | ANSWER NAME |
> | | = 10.1.168.192.IN-ADDR.ARPA |
> | | ANSWER PTRDNAME |
> | | = A.example.org |
> | | AUTHORITY Name |
> | | = 1.168.192.IN-ADDR.ARPA |
> | | AUTHORITY NSDNAME |
> | | = NS5.example.org |
> | | ADDITIONAL Name |
> | | = NS5.example.org |
> | | ADDITIONAL Address |
> | | = 192.168.1.50 |
> |<-----------------------------| v
> | 10. Recv Standard query |
> | response |
> | QNAME |
> | = 10.1.168.192.IN-ADDR.ARPA|
> | QTYPE=PTR |
> | ANSWER NAME |
> | = 10.1.168.192.IN-ADDR.ARPA|
> | ANSWER PTRDNAME |
> | = A.example.org |
> | AUTHORITY Name |
> | = 1.168.192.IN-ADDR.ARPA |
> | AUTHORITY NSDNAME |
> | = NS5.example.org |
> | ADDITIONAL Name |
> | = NS5.example.org |
> | ADDITIONAL Address |
> | = 192.168.1.50 |
> v v
>
>
>Best regards,
>
>
>