[ZBX-20143] net.dns.record item with invald DNS Server leads to Agent unavailable Created: 2021 Oct 29  Updated: 2024 Apr 10  Resolved: 2022 Jan 06

Status: Closed
Project: ZABBIX BUGS AND ISSUES
Component/s: Agent (G), Server (S)
Affects Version/s: 5.4.7
Fix Version/s: 5.0.20rc1, 5.4.10rc1, 6.0.0beta2, 6.0 (plan)

Type: Problem report Priority: Major
Reporter: Aleksey Volodin Assignee: Dmitrijs Goloscapovs
Resolution: Fixed Votes: 0
Labels: None
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified

Issue Links:
Causes
Team: Team A
Sprint: Sprint 82 (Nov 2021), Sprint 83 (Dec 2021), Sprint 84 (Jan 2022)
Story Points: 1

 Description   

Steps to reproduce:

  1. Add item with net.dns.record[172.23.2.100,google.ch,NS,30,1,tcp] key. Notice that 172.23.2.100 are not valid DNS server.

Please notice - timeout parameter in this key does no take affect for this issue. Tested with 1 an 30 - result the same.

Result:

Whole Agent become unavailable.

Get value from agent failed: ZBX_TCP_READ() timed out
3746888:20211028:102029.032 Zabbix agent item "net.dns.record[172.23.2.100,google.ch,NS,30,1,tcp]" on host "DNS Test" failed: first network error, wait for 15 seconds
 3746888:20211028:102044.037 resuming Zabbix agent checks on host "DNS Test": connection restored
 3746888:20211028:102048.037 Zabbix agent item "net.dns.record[172.23.2.100,google.ch,NS,30,1,tcp]" on host "DNS Test" failed: first network error, wait for 15 seconds
 3746887:20211028:102058.308 Zabbix agent item "system.uptime" on host "Zabbix server" failed: first network error, wait for 15 seconds
 3746888:20211028:102107.039 Zabbix agent item "net.dns.record[172.23.2.100,google.ch,NS,30,1,tcp]" on host "DNS Test" failed: another network error, wait for 15 seconds
 3746888:20211028:102117.040 Zabbix agent item "system.cpu.util[,iowait]" on host "Zabbix server" failed: another network error, wait for 15 seconds
 3746888:20211028:102126.041 Zabbix agent item "net.dns.record[172.23.2.120,google.ch,NS,30,1,tcp]" on host "DNS Test" failed: another network error, wait for 15 seconds
 3746888:20211028:102136.042 Zabbix agent item "system.swap.size[,free]" on host "Zabbix server" failed: another network error, wait for 15 seconds
 3746888:20211028:102145.043 temporarily disabling Zabbix agent checks on host "DNS Test": interface unavailable
 3746888:20211028:102155.045 temporarily disabling Zabbix agent checks on host "Zabbix server": interface unavailable
 3746888:20211028:102245.054 enabling Zabbix agent checks on host "DNS Test": interface became available
 3746888:20211028:102249.055 Zabbix agent item "net.dns.record[172.23.2.100,google.ch,NS,30,1,tcp]" on host "DNS Test" failed: first network error, wait for 15 seconds
 3746888:20211028:102255.056 enabling Zabbix agent checks on host "Zabbix server": interface became available
 3746888:20211028:102308.059 Zabbix agent item "net.dns.record[172.23.2.100,google.ch,NS,30,1,tcp]" on host "DNS Test" failed: another network error, wait for 15 seconds
 3746884:20211028:102308.543 Zabbix agent item "system.cpu.util[,guest_nice]" on host "Zabbix server" failed: first network error, wait for 15 seconds
 3746888:20211028:102327.061 Zabbix agent item "system.cpu.util[,steal]" on host "Zabbix server" failed: another network error, wait for 15 seconds
 3746888:20211028:102331.062 Zabbix agent item "net.dns.record[172.23.2.120,google.ch,NS,30,1,tcp]" on host "DNS Test" failed: another network error, wait for 15 seconds
 3746888:20211028:102344.131 resuming Zabbix agent checks on host "Zabbix server": connection restored
 3746888:20211028:102350.133 temporarily disabling Zabbix agent checks on host "DNS Test": interface unavailable
 3746886:20211028:102358.616 Zabbix agent item "system.uptime" on host "Zabbix server" failed: first network error, wait for 15 seconds
 3746886:20211028:102405.617 Zabbix agent item "system.cpu.num" on host "Zabbix server" failed: first network error, wait for 15 seconds
 3746888:20211028:102424.137 Zabbix agent item "system.cpu.util[,guest]" on host "Zabbix server" failed: another network error, wait for 15 seconds
 3746888:20211028:102443.139 Zabbix agent item "system.swap.size[,pfree]" on host "Zabbix server" failed: another network error, wait for 15 seconds
 3746888:20211028:102453.761 enabling Zabbix agent checks on host "DNS Test": interface became available
 3746888:20211028:102457.761 Zabbix agent item "net.dns.record[172.23.2.100,google.ch,NS,30,1,tcp]" on host "DNS Test" failed: first network error, wait for 15 seconds
 3746888:20211028:102502.762 temporarily disabling Zabbix agent checks on host "Zabbix server": interface unavailable
 3746888:20211028:102516.763 Zabbix agent item "net.dns.record[172.23.2.100,google.ch,NS,30,1,tcp]" on host "DNS Test" failed: another network error, wait for 15 seconds
 3746888:20211028:102535.771 Zabbix agent item "net.dns.record[172.23.2.120,google.ch,NS,30,1,tcp]" on host "DNS Test" failed: another network error, wait for 15 seconds
 3746888:20211028:102554.773 temporarily disabling Zabbix agent checks on host "DNS Test": interface unavailable
126161:20211029:165821.230 Requested [net.dns.record[172.23.2.100,google.ch,NS,1,1,tcp]]
126161:20211029:170009.969 Sending back [ZBX_NOTSUPPORTED: Cannot perform DNS query.]
time zabbix_agentd -t net.dns.record[172.23.2.100,google.ch,NS,1,1,tcp]
net.dns.record[172.23.2.100,google.ch,NS,1,1,tcp] [m|ZBX_NOTSUPPORTED] [Cannot perform DNS query.]
real 2m11.415s
user 0m0.008s
sys 0m0.005s

 

Expected:

Some error message.

 



 Comments   
Comment by Vladislavs Sokurenko [ 2021 Dec 29 ]

Issue occurs due to tcp connection timeout which is roughly 2 minutes, workaround is either to fork the metric or to set alarm before calling res_nsend

Comment by Dmitrijs Goloscapovs [ 2022 Jan 05 ]

Available in versions:

Comment by Benjamin Rechsteiner [ 2022 Jul 01 ]

is it possible that the same problem exists for net.dns?

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