SV_RFC2308_7_1_cache_server_fail - Resolver cache a server failure response
Verify that a NUT caches a server failure response.
- Server failures fall into two major classes. The first is where a
server can determine that it has been misconfigured for a zone. This
may be where it has been listed as a server, but not configured to be
a server for the zone, or where it has been configured to be a server
for the zone, but cannot obtain the zone data for some reason. This
can occur either because the zone file does not exist or contains
errors, or because another server from which the zone should have
been available either did not respond or was unable or unwilling to
supply the zone.
- The second class is where the server needs to obtain an answer from
elsewhere, but is unable to do so, due to network failures, other
servers that don't reply, or return server failure errors, or
similar.
- In either case a resolver MAY cache a server failure response. If it
does so it MUST NOT cache it for longer than five (5) minutes, and it
MUST be cached against the specific query tuple "query name, type,
class, server IP address".
Caching Server
SV_RFC2308_7_1_cache_server_fail.seq [-tooloption ...]: KOI tool option
See also DNSConfig.pm
This test sequence is following.
<-------------- TN --------------->
DNS Client1 (TN) DNS Server1 (NUT) DNS Server2 DNS Server3 DNS Server4
| | | | |
|----------------------------->| | | |
| 1. Send standard query | | | |
| QNAME=A.example.org | | | |
| QTYPE=A | | | |
| | | | |
| |-------------------------------->| | |
| | 2. Recv standard query | | |
| | QNAME=A.example.org | | |
| | QTYPE=A | | |
| | | | |
| |<--------------------------------| | |
| | 3. Send standard query response | | |
| | QNAME=A.example.org | | |
| | QTYPE=A | | |
| | AUTHORITY Name=org | | |
| | AUTHORITY Name Server | | |
| | =NS3.example.org | | |
| | ADDITIONAL Name | | |
| | =NS3.example.org | | |
| | ADDITIONAL Address | | |
| | =192.168.1.30 | | |
| | | | |
| | v | |
| | | |
| |-------------------------------------------->| |
| | 4. Recv standard query | |
| | QNAME=A.example.org | |
| | QTYPE=A | |
| | | |
| |<--------------------------------------------| |
| | 5. Send standard query response | |
| | QNAME=A.example.org | |
| | QTYPE=A | |
| | AUTHORITY Name=example.org | |
| | AUTHORITY Name Server | |
| | = NS4.example.org | |
| | ADDITIONAL Name | |
| | = NS4.example.org | |
| | ADDITIONAL Address | |
| | = 192.168.1.40 | |
| | | |
| | v |
| | |
| |-------------------------------------------------------->|
| | 6. Send standard query |
| | QNAME=A.example.org |
| | QTYPE=A |
| | |
| |<--------------------------------------------------------|
| | 7. Send standard query response|
| | RCODE=2(Server failure) |
| | QNAME=A.example.org |
| | QTYPE=A |
| | |
| | |
|<-----------------------------| |
| 8. Standard query response | |
| RCODE= 2(Server failure) | |
| QNAME= A.example.org | |
| QTYPE=A | |
| | |
|----------------------------->| |
| 9. Send standard query | |
| QNAME=A.example.org | |
| QTYPE=A | |
| | |
|<-----------------------------| |
| 10. Standard query response | |
| RCODE= 2(Server failure) | |
| QNAME= A.example.org | |
| QTYPE=A | |
| | |
v v v
1. TN send standard query QNAME=A.example.org, QTYPE=A to NUT.
2. NUT transmits standard query to DNS Server2 (TN: root name server) (Judgment *2)
3. TN send query response to NUT w/ AUTHORITY Name=org, AUTHORITY Name Server=NS3.example.org.
4. NUT transmits standard query QNAME=A.example.org, QTYPE=A to DNS Server3 (TN: NS3.example.org) (Judgment *4)
5. TN send query response to NUT w/ AUTHORITY Name=example.org, AUTHORITY Name Server=NS4.example.org.
6. NUT transmits standard query QNAME=A.example.org, QTYPE=A to DNS Server4 (TN: NS4.example.org) (Judgment *6)
7. TN send query response(server failure) to NUT.
8. NUT transmits query response(server failure) to DNS Client1 (TN) (Judgment *8)
9. TN send standard query QNAME=A.example.org, QTYPE=A to NUT.
10. NUT transmits query response(server failure) to DNS Client1 (TN) (Judgment *10)
- Packet Description
- 1st packet.
Standard query from DNS Client1 (TN) to Server1 (NUT)
|
IP Header |
Source Address |
CL1_NETZ |
Destination Address |
NUT_NETZ |
UDP Header |
Src Port |
2000 |
Dst Port |
53 |
DNS Header |
ID |
0x1000 |
QR |
0 |
OPCODE |
0 |
AA |
0 |
TC |
0 |
RD |
1 |
RA |
0 |
Z |
0 |
RCODE |
0 |
QDCOUNT |
1 |
ANCOUNT |
0 |
NSCOUNT |
0 |
ARCOUNT |
0 |
DNS Question section |
QNAME |
A.example.org |
QTYPE |
A (0x0001) |
QCLASS |
IN (0x0001) |
- 2nd packet.
Standard query from DNS Server1 (NUT) to Server2 (TN)
|
IP Header |
Source Address |
NUT_NETZ |
Destination Address |
SV2_NETY |
UDP Header |
Src Port |
ANY |
Dst Port |
53 |
DNS Header |
ID |
ANY |
QR |
0 |
OPCODE |
0 |
AA |
ANY |
TC |
0 |
RD |
0 |
RA |
ANY |
Z |
ANY |
RCODE |
ANY |
QDCOUNT |
1 |
ANCOUNT |
0 |
NSCOUNT |
0 |
ARCOUNT |
ANY |
DNS Question section |
QNAME |
A.example.org |
QTYPE |
A (0x0001) |
QCLASS |
IN (0x0001) |
- 3rd packet.
Standard query response from DNS Server2 (TN) to Server1 (NUT)
|
IP Header |
Source Address |
SV2_NETY |
Destination Address |
NUT_NETZ |
UDP Header |
Src Port |
53 |
Dst Port |
Value that NUT uses |
DNS Header |
ID |
Value that NUT uses |
QR |
1 |
OPCODE |
0 |
AA |
0 |
TC |
0 |
RD |
0 |
RA |
0 |
Z |
0 |
RCODE |
0 |
QDCOUNT |
1 |
ANCOUNT |
0 |
NSCOUNT |
1 |
ARCOUNT |
1 |
DNS Question section |
QNAME |
A.example.org
|
QTYPE |
A (0x0001) |
QCLASS |
IN (0x0001) |
DNS Authority section |
NAME |
org (Pointer 0xC016) |
TYPE |
NS (0x0002) |
CLASS |
IN (0x0001) |
TTL |
1 day (86400) |
RDLENGTH |
6 |
NSDNAME |
NS3.example.org (NS3 + Pointer 0xC00E) |
DNS Additional section |
NAME |
NS3.example.org (Pointer 0xC02B) |
TYPE
|
A (0x0001) |
CLASS |
IN (0x0001) |
TTL |
1 day (86400) |
RDLENGTH |
4 |
ADDRESS |
192.168.1.30 |
- 4th packet.
Standard query from DNS Server1 (NUT) to Server3 (TN)
|
IP Header |
Source Address |
NUT_NETZ |
Destination Address |
SV3_NETY |
UDP Header |
Src Port |
ANY |
Dst Port |
53 |
DNS Header |
ID |
ANY |
QR |
0 |
OPCODE |
0 |
AA |
ANY |
TC |
0 |
RD |
0 |
RA |
ANY |
Z |
ANY |
RCODE |
ANY |
QDCOUNT |
1 |
ANCOUNT |
0 |
NSCOUNT |
0 |
ARCOUNT |
ANY |
DNS Question section |
QNAME |
A.example.org |
QTYPE |
A (0x0001) |
QCLASS |
IN (0x0001) |
- 5th packet.
Standard query response from DNS Server3 (TN) to Server1 (NUT)
|
IP Header |
Source Address |
SV3_NETY |
Destination Address |
NUT_NETZ |
UDP Header |
Src Port |
Value that NUT uses |
Dst Port |
53 |
DNS Header |
ID |
Value that NUT uses |
QR |
1 |
OPCODE |
0 |
AA |
0 |
TC |
0 |
RD |
0 |
RA |
0 |
Z |
0 |
RCODE |
0 |
QDCOUNT |
1 |
ANCOUNT |
0 |
NSCOUNT |
1 |
ARCOUNT |
1 |
DNS Question section |
QNAME |
A.example.org
|
QTYPE |
A (0x0001) |
QCLASS |
IN (0x0001) |
DNS Authority section |
NAME |
example.org (Pointer 0xC00E) |
TYPE |
NS (0x0002) |
CLASS |
IN (0x0001) |
TTL |
1 day (86400) |
RDLENGTH |
6 |
NSDNAME |
NS4.example.org (NS4 + Pointer 0xC00E) |
DNS Additional section |
NAME |
NS4.example.org (Pointer 0xC02B) |
TYPE
|
A (0x0001) |
CLASS |
IN (0x0001) |
TTL |
1 day (86400) |
RDLENGTH |
4 |
ADDRESS |
192.168.1.40 |
- 6th packet.
Standard query from DNS Server1 (NUT) to Server4 (TN)
|
IP Header |
Source Address |
NUT_NETZ |
Destination Address |
SV4_NETY |
UDP Header |
Src Port |
ANY |
Dst Port |
53 |
DNS Header |
ID |
ANY |
QR |
0 |
OPCODE |
0 |
AA |
ANY |
TC |
0 |
RD |
0 |
RA |
ANY |
Z |
ANY |
RCODE |
ANY |
QDCOUNT |
1 |
ANCOUNT |
0 |
NSCOUNT |
0 |
ARCOUNT |
ANY |
DNS Question section |
QNAME |
A.example.org |
QTYPE |
A (0x0001) |
QCLASS |
IN (0x0001) |
- 7th packet.
Standard query response from DNS Server4 (TN) to Server1 (NUT)
|
IP Header |
Source Address |
SV4_NETY |
Destination Address |
NUT_NETZ |
UDP Header |
Src Port |
Value that NUT uses |
Dst Port |
53 |
DNS Header |
ID |
Value that NUT uses |
QR |
1 |
OPCODE |
0 |
AA |
1 |
TC |
0 |
RD |
0 |
RA |
1 |
Z |
0 |
RCODE |
2 |
QDCOUNT |
1 |
ANCOUNT |
0 |
NSCOUNT |
0 |
ARCOUNT |
0 |
DNS Question section |
QNAME |
A.example.org
|
QTYPE |
A (0x0001) |
QCLASS |
IN (0x0001) |
- 8th packet.
Standard query response from DNS Server1 (NUT) to Client1 (TN)
|
IP Header |
Source Address |
NUT_NETZ |
Destination Address |
CL1_NETZ |
UDP Header |
Src Port |
53 |
Dst Port |
2000 |
DNS Header |
ID |
0x1000 |
QR |
1 |
OPCODE |
0 |
AA |
0 |
TC |
0 |
RD |
1 |
RA |
1 |
Z |
0 |
RCODE |
2 |
QDCOUNT |
1 |
ANCOUNT |
0 |
NSCOUNT |
0 |
ARCOUNT |
0 |
DNS Question section |
QNAME |
A.example.org
|
QTYPE |
A (0x0001) |
QCLASS |
IN (0x0001) |
- 9th packet.
Standard query from DNS Client1 (TN) to Server1 (NUT)
|
IP Header |
Source Address |
CL1_NETZ |
Destination Address |
NUT_NETZ |
UDP Header |
Src Port |
2000 |
Dst Port |
53 |
DNS Header |
ID |
0x1001 |
QR |
0 |
OPCODE |
0 |
AA |
0 |
TC |
0 |
RD |
1 |
RA |
0 |
Z |
0 |
RCODE |
0 |
QDCOUNT |
1 |
ANCOUNT |
0 |
NSCOUNT |
0 |
ARCOUNT |
0 |
DNS Question section |
QNAME |
A.example.org |
QTYPE |
A (0x0001) |
QCLASS |
IN (0x0001) |
- 10th packet.
Standard query response from DNS Server1 (NUT) to Client1 (TN)
|
IP Header |
Source Address |
NUT_NETZ |
Destination Address |
CL1_NETZ |
UDP Header |
Src Port |
53 |
Dst Port |
2000 |
DNS Header |
ID |
0x1001 |
QR |
1 |
OPCODE |
0 |
AA |
0 |
TC |
0 |
RD |
1 |
RA |
1 |
Z |
0 |
RCODE |
2 |
QDCOUNT |
1 |
ANCOUNT |
0 |
NSCOUNT |
0 |
ARCOUNT |
0 |
DNS Question section |
QNAME |
A.example.org
|
QTYPE |
A (0x0001) |
QCLASS |
IN (0x0001) |
- Exp.
NUT_NETZ |
DNS Server1's (NUT) Net-z address |
CL1_NETZ |
DNS Client1's (TN) Net-z address |
SV2_NETY |
DNS Server2's (TN) Net-y address |
SV3_NETY |
DNS Server3's (TN) Net-y address |
SV4_NETY |
DNS Server4's (TN) Net-y address |
2. Received standard query including QNAME=A.example.org, QTYPE=A.
4. Received standard query including QNAME=A.example.org, QTYPE=A.
6. Received standard query including QNAME=A.example.org, QTYPE=A.
8. Received standard query response(Server failure).
10. Received standard query response(Server failure).
None
RFC2308 Negative Caching of DNS Queries (DNS NCACHE)
7.1 Server Failure (OPTIONAL)