CL_RFC2308_7_2_not_cache_dead_server - Caching of dead server indication for query tuple
Verify that a NUT caches a dead server indication for the specific query tuple
- Dead / Unreachable servers are servers that fail to respond in any
- way to a query or where the transport layer has provided an
- indication that the server does not exist or is unreachable. A
- server may be deemed to be dead or unreachable if it has not
- responded to an outstanding query within 120 seconds.
- A server MAY cache a dead server indication. If it does so it MUST
- NOT be deemed dead for longer than five (5) minutes. The indication
- MUST be stored against query tuple "query name, type, class, server
- IP address" unless there was a transport layer indication that the
- server does not exist, in which case it applies to all queries to
- that specific IP address.
Client (with Caching function)
CL_RFC2308_7_2_not_cache_dead_server.seq [-tooloption ...]: KOI tool option
See also DNSConfig.pm
AP Server1(TN):A.example.com DNS Server1(TN)
|3ffe:501:ffff:101::10 |3ffe:501:ffff:101::20
|192.168.1.10 |192.168.1.20
| |
Net-y --+--------+-----------------------+-------- 3ffe:501:ffff:101::/64
| 192.168.1/24
|
|
ROUTER1(TN)
|3ffe:501:ffff:100::1
|192.168.0.1
|
Net-z --+--------+-------------------------------- 3ffe:501:ffff:100::/64
| 192.168.0/24
DNS Client1(NUT)
3ffe:501:ffff:100:XXXX
192.168.0.10
XXXX: EUI64 address
Setup
Set the DNS Server1(TN)'s address on NUT as above mentioned Network Topology.
Pre-Sequence
In order to send the query for A type(IN class) of AP Server1(TN):A.example.com to the DNS Server1(TN),
NUT is configured.
This test sequence is following.
DNS Client1 (NUT) DNS Server1 (TN)
| |
|--------------------------------------------->|
| 1. Send standard query |
| QNAME=A.example.com |
| QTYPE=A |
| |
| X <------------------------------------------|
| 2. Standard query response |
| No response within 120 seconds |
| |
|--------------------------------------------->|
| 3. Send standard query |
| QNAME=B.example.com |
| QTYPE=A |
| |
v v
1. NUT send standard query to TN.
Judgment (Check *1)
2. TN doesn't send standard query response to NUT within 120 seconds.
3. NUT send standard query to TN after 120 seconds from 1.
Judgment (Check *3)
Packet Description
1st Packet
|
1. Standard query from DNS Client1 (NUT) to DNS Server1 (TN)
|
| IP Header |
Source Address |
NUT_NETZ |
| Destination Address |
SV_NETY |
UDP Header
|
Src Port
|
any
|
Dst Port
|
53
|
DNS Header
|
ID |
any |
QR
|
0
|
OPCODE
|
0
|
AA
|
any
|
| TC |
0 |
| RD |
any |
RA
|
any
|
Z
|
any
|
RCODE
|
any
|
QDCOUNT
|
1
|
ANCOUNT
|
0
|
NSCOUNT
|
0
|
ARCOUNT
|
any
|
DNS Question section
|
QNAME |
A.example.com
|
QTYPE
|
A (0x0001)
|
QCLASS
|
IN (0x0001)
|
3rd Packet
|
4. Standard query from DNS Client1 (NUT) to DNS Server1 (TN)
|
| IP Header |
Source Address |
NUT_NETZ |
| Destination Address |
SV_NETY |
UDP Header
|
Src Port
|
any
|
Dst Port
|
53
|
DNS Header
|
ID |
any |
QR
|
0
|
OPCODE
|
0
|
AA
|
any
|
| TC |
0 |
| RD |
any |
RA
|
any
|
Z
|
any
|
RCODE
|
any
|
QDCOUNT
|
1
|
ANCOUNT
|
0
|
NSCOUNT
|
0
|
ARCOUNT
|
0
|
DNS Question section
|
QNAME |
B.example.com
|
QTYPE
|
A (0x0001)
|
QCLASS
|
IN (0x0001)
|
NUT_NETZ : DNS Client1(NUT)'s address
SV_NETY : DNS Server1(TN)'s address
1. Received standard query QNAME=A.example.com from NUT.
3. Received standard query QNAME=B.example.com from NUT.
If NUT has cache function, clear the cache.
RFC2308 Negative Caching of DNS Queries (DNS NCACHE)
7.2 Dead / Unreachable Server (OPTIONAL)