We have the following DNS Server configuration with the MSR3012 with IP and DNS given by DHCP. The HPE_1 and HPE_2 devices are linked to level 3 on a point-to-point ip interface:
CONFIG HPE_1
interface g0/0
ip address 192.168.134.1 255.255.255.0
no proxy-arp enable
no ip irdp
exit
interface g0/1
ip address 1.1.1.1 255.255.255.252
no proxy-arp enable
no ip irdp
exit
dns domain Prueba
dns server 1.1.1.2
ip host server_1 2.2.2.2
ip host server_2 3.3.3.3
ip host dns1 1.1.1.1
dhcp server ip-pool 1
network 192.168.134.0 mask 255.255.255.0
expired day 10 hour 12
domain-name Prueba
dns-list 192.168.134.1 1.1.1.2
gateway-list 192.168.134.1
quit
ip route-static 2.2.2.2 255.255.255.255 1.1.1.2
ip route-static 3.3.3.3 255.255.255.255 1.1.1.2
CONFIG HPE_2
interface g0/0
ip address 1.1.1.2 255.255.255.252
no proxy-arp enable
no ip irdp
exit
dns domain Prueba
ip host dns2 1.1.1.2
interface LoopBack 1
description server_1
ip address 2.2.2.2 32
undo shutdown
exit
interface LoopBack 2
description server_2
ip address 3.3.3.3 32
undo shutdown
exit
ip route-static 192.168.134.0 255.255.255.0 1.1.1.1
HPE 1
[HPE_1]display dns host
Type:
D: Dynamic S: Static
Total number: 3
No. Host name Type TTL Query type IP addresses
1 dns1 D 3412 A 1.1.1.1
2 dns2 D 2582 A 1.1.1.2
3 server_1 D 3521 A 2.2.2.2
[HPE_1]ping server_2
Ping server_2 (3.3.3.3): 56 data bytes, press CTRL_C to break
56 bytes from 3.3.3.3: icmp_seq=0 ttl=255 time=0.320 ms
*Jun 15 23:35:16:864 2017 HPE_1 DNS/7/EVENT: Starting A resolving for server_2
*Jun 15 23:35:16:864 2017 HPE_1 DNS/7/EVENT: Trying to resolve server_2 in local database
*Jun 15 23:35:16:864 2017 HPE_1 DNS/7/EVENT: Trying to resolve server_2.Prueba in dynamic cache
*Jun 15 23:35:16:864 2017 HPE_1 DNS/7/EVENT: Trying to resolve server_2 in dynamic cache
*Jun 15 23:35:16:864 2017 HPE_1 DNS/7/EVENT: Trying to resolve server_2.Prueba by contacting DNS server 1.1.1.2 through UDP
*Jun 15 23:35:16:865 2017 HPE_1 DNS/7/PACKET: Sent:
Header:
ID = 26934
QR = 0, OpCode = 0, AA = 0, TC = 0, RD = 1
RA = 0, Z = 0, AD = 0, CD = 0, RCode = 0
QDCount = 1
ANCount = 0
NSCount = 0
ARCount = 0
*Jun 15 23:35:16:865 2017 HPE_1 DNS/7/PACKET: Sent:
Question:
QName = server_2.Prueba
QType = A (1)
QClass = IN (1)
*Jun 15 23:35:16:865 2017 HPE_1 DNS/7/EVENT: Waiting 2 seconds for server response
*Jun 15 23:35:16:866 2017 HPE_1 DNS/7/PACKET: Received:
Header:
ID = 26934
QR = 1, OpCode = 0, AA = 0, TC = 0, RD = 1
RA = 0, Z = 0, AD = 0, CD = 0, RCode = 2
QDCount = 1
ANCount = 0
NSCount = 0
ARCount = 0
*Jun 15 23:35:16:866 2017 HPE_1 DNS/7/PACKET: Received:
Question:
QName = server_2.Prueba
QType = A (1)
QClass = IN (1)
*Jun 15 23:35:16:866 2017 HPE_1 DNS/7/EVENT: Received an answer: QName = server_2.Prueba, ID = 26934
*Jun 15 23:35:16:866 2017 HPE_1 DNS/7/EVENT: The answer is invalid.
*Jun 15 23:35:16:866 2017 HPE_1 DNS/7/EVENT: Trying to resolve server_2 by contacting DNS server 1.1.1.2 through UDP
*Jun 15 23:35:16:867 2017 HPE_1 DNS/7/PACKET: Sent:
Header:
ID = 32495
QR = 0, OpCode = 0, AA = 0, TC = 0, RD = 1
RA = 0, Z = 0, AD = 0, CD = 0, RCode = 0
QDCount = 1
ANCount = 0
NSCount = 0
ARCount = 0
*Jun 15 23:35:16:867 2017 HPE_1 DNS/7/PACKET: Sent:
Question:
QName = server_2
QType = A (1)
QClass = IN (1)
*Jun 15 23:35:16:867 2017 HPE_1 DNS/7/EVENT: Waiting 2 seconds for server response
*Jun 15 23:35:16:868 2017 HPE_1 DNS/7/PACKET: Received:
Header:
ID = 32495
QR = 1, OpCode = 0, AA = 0, TC = 0, RD = 1
RA = 0, Z = 0, AD = 0, CD = 0, RCode = 0
QDCount = 1
ANCount = 1
NSCount = 0
ARCount = 0
*Jun 15 23:35:16:868 2017 HPE_1 DNS/7/PACKET: Received:
Question:
QName = server_2
QType = A (1)
QClass = IN (1)
*Jun 15 23:35:16:868 2017 HPE_1 DNS/7/PACKET: Received:
Answer:
Name = server_2
Type = A (1)
Class = IN (1)
TTL = 3600
RDLength = 4
RData = 3.3.3.3
*Jun 15 23:35:16:868 2017 HPE_1 DNS/7/EVENT: Received an answer: QName = server_2, ID = 32495
*Jun 15 23:35:16:868 2017 HPE_1 DNS/7/EVENT: Trying to resolve server_2 in dynamic cache
*Jun 15 23:35:16:868 2017 HPE_1 DNS/7/EVENT: Added a dynamic DNS entry server_2
*Jun 15 23:35:16:868 2017 HPE_1 DNS/7/EVENT: Successfully resolved server_2: host name is server_2, address is 3.3.3.3
*Jun 15 23:35:16:868 2017 HPE_1 DNS/7/EVENT: Trying to resolve server_2.Prueba in dynamic cache
*Jun 15 23:35:16:869 2017 HPE_1 DNS/7/EVENT: Trying to resolve server_2 in dynamic cache
56 bytes from 3.3.3.3: icmp_seq=1 ttl=255 time=0.286 ms
56 bytes from 3.3.3.3: icmp_seq=2 ttl=255 time=0.235 ms
56 bytes from 3.3.3.3: icmp_seq=3 ttl=255 time=0.262 ms
56 bytes from 3.3.3.3: icmp_seq=4 ttl=255 time=0.239 ms
--- Ping statistics for server_2 ---
5 packet(s) transmitted, 5 packet(s) received, 0.0% packet loss
round-trip min/avg/max/std-dev = 0.235/0.268/0.320/0.032 ms
[HPE_1]%Jun 15 23:35:17:673 2017 HPE_1 PING/6/PING_STATISTICS: Ping statistics for server_2: 5 packet(s) transmitted, 5 packet(s) received, 0.0% packet loss, round-trip min/avg/max/std-dev = 0.235/0.268/0.320/0.032 ms.
------------------------------------------------------------------------------------------------------------------
HPE 2
[HPE_2]
*Jun 15 23:33:20:659 2017 HPE_2 DNS/7/PACKET: Received:
Header:
ID = 26934
QR = 0, OpCode = 0, AA = 0, TC = 0, RD = 1
RA = 0, Z = 0, AD = 0, CD = 0, RCode = 0
QDCount = 1
ANCount = 0
NSCount = 0
ARCount = 0
*Jun 15 23:33:20:659 2017 HPE_2 DNS/7/PACKET: Received:
Question:
QName = server_2.Prueba
QType = A (1)
QClass = IN (1)
*Jun 15 23:33:20:660 2017 HPE_2 DNS/7/EVENT: DNS proxy received a request for resolving server_2.Prueba
*Jun 15 23:33:20:660 2017 HPE_2 DNS/7/EVENT: Trying to resolve server_2.Prueba in local database
*Jun 15 23:33:20:660 2017 HPE_2 DNS/7/EVENT: Trying to resolve server_2.Prueba in dynamic cache
*Jun 15 23:33:20:660 2017 HPE_2 DNS/7/EVENT: No DNS server is found.
*Jun 15 23:33:20:660 2017 HPE_2 DNS/7/EVENT: Failed to resolve server_2.Prueba
*Jun 15 23:33:20:660 2017 HPE_2 DNS/7/EVENT: DNS proxy sent a reply for resolving server_2.Prueba
*Jun 15 23:33:20:660 2017 HPE_2 DNS/7/PACKET: Sent:
Header:
ID = 26934
QR = 1, OpCode = 0, AA = 0, TC = 0, RD = 1
RA = 0, Z = 0, AD = 0, CD = 0, RCode = 2
QDCount = 1
ANCount = 0
NSCount = 0
ARCount = 0
*Jun 15 23:33:20:660 2017 HPE_2 DNS/7/PACKET: Sent:
Question:
QName = server_2.Prueba
QType = A (1)
QClass = IN (1)
*Jun 15 23:33:20:660 2017 HPE_2 DNS/7/EVENT: Trying to resolve server_2.Prueba in dynamic cache
*Jun 15 23:33:20:660 2017 HPE_2 DNS/7/EVENT: Trying to resolve server_2.Prueba.Prueba in dynamic cache
*Jun 15 23:33:20:661 2017 HPE_2 DNS/7/PACKET: Received:
Header:
ID = 32495
QR = 0, OpCode = 0, AA = 0, TC = 0, RD = 1
RA = 0, Z = 0, AD = 0, CD = 0, RCode = 0
QDCount = 1
ANCount = 0
NSCount = 0
ARCount = 0
*Jun 15 23:33:20:661 2017 HPE_2 DNS/7/PACKET: Received:
Question:
QName = server_2
QType = A (1)
QClass = IN (1)
*Jun 15 23:33:20:661 2017 HPE_2 DNS/7/EVENT: DNS proxy received a request for resolving server_2
*Jun 15 23:33:20:661 2017 HPE_2 DNS/7/EVENT: Trying to resolve server_2 in local database
*Jun 15 23:33:20:661 2017 HPE_2 DNS/7/EVENT: DNS proxy sent a reply for resolving server_2
*Jun 15 23:33:20:662 2017 HPE_2 DNS/7/PACKET: Sent:
Header:
ID = 32495
QR = 1, OpCode = 0, AA = 0, TC = 0, RD = 1
RA = 0, Z = 0, AD = 0, CD = 0, RCode = 0
QDCount = 1
ANCount = 1
NSCount = 0
ARCount = 0
*Jun 15 23:33:20:662 2017 HPE_2 DNS/7/PACKET: Sent:
Question:
QName = server_2
QType = A (1)
QClass = IN (1)
*Jun 15 23:33:20:662 2017 HPE_2 DNS/7/PACKET: Sent:
Answer:
Name = server_2
Type = A (1)
Class = IN (1)
TTL = 3600
RDLength = 4
RData = 3.3.3.3
What maximum lifetime are these DNS entries saved in HPE1, I see that there is a TTL in the display. What ttl have dns resolutions that caches the proxy-dns? Is there a maximum size?
In Debug does not appear the source of the DNS request, how could it be visualized?
Regards.
#DNS#MSR#ttl