Issue in CISCO2951/K9 Router catalyst 2000

[majdi00011]

Hi gents 

I've used CISCO2951/K9 router in hotel, and connect main internet to it and then share to admin area. However, time to time I faced issue in internet can't load any page. I checked router logs and found below 

*Aug 18 08:23:34.414: %SYS-3-CPUHOG: Task is running for (2000)msecs, more than (2000)msecs (4/0),process = DNS Server.
-Traceback= 0xB06B4A4z 0x5A00870z 0x5C51DFCz 0x5C51F00z 0x5C54974z 0x4E7B700z 0x4E62620z
*Aug 18 08:23:36.429: %SYS-3-CPUHOG: Task is running for (4000)msecs, more than (2000)msecs (8/0),process = DNS Server.
-Traceback= 0x716048Cz 0x5A00B34z 0x5C51F40z 0x5C54974z 0x4E7B700z 0x4E62620z

Issue still there until reboot the router then internet work properly. After while again same issue and same thing need to restart the router. 

Any idea for this issue and how to solve it ? attached for logs from router .

Thanks in advance

Majdi 

[Giuseppe Larosa]

Hello  @majdi00011 ,

your configuration looks like fine you have a default static route using an IP next-hop so your router is not relying on Proxy ARP.

You have configured two public IP DNS servers:

p name-server 86.51.35.17

ip name-server 86.51.35.18

the log error are of type

-Traceback= 0xB06C25Cz 0x5A00904z 0x5C51F40z 0x5C54974z 0x4E7B700z 0x4E62620z
*Aug 18 08:22:24.190: %SYS-3-CPUHOG: Task is running for (2000)msecs, more than (2000)msecs (4/0),process = DNS Server.

all this leads to think of a software bug.

post a show version but a Cisco 2951 is likely in End of Support

Edit:

I see the following line:

ip dns server

try to remove it and have clients to point directly to public DNS server (if possible)

Hope to help

Giuseppe

[Richard Burts]

Majdi

The message about CPU HOG looks like it might be significant. But the really significant thing is the message about "Traceback". Traceback is ALWAYS an indication of a software problem. 

While you may make some tweaks in your config, the config is not the problem. The problem is the code that the router is running. 

[majdi00011]

Thanks Rick 

If code has the problem, how can I do solution ! Also, is there a chance HW has issue and need to replace by new ?

BR

Majdi

[Richard Burts]

Majdi

You are welcome. You asked 2 questions. Here are my responses:

- "If code has the problem, how can I do solution" If the code has a problem, one solution would be to obtain a different/newer version of code and hope that it addresses the issue. In your case I wonder if replacing the code with a newer version is a realistic alternative. If replacing code is not a realistic solution, then perhaps tweaking the config might help. As others in this discussion have suggested the issue seems to be about DNS, so perhaps changing DNS aspects might probvide some relief. 

- "is there a chance HW has issue and need to replace by new" This one is pretty easy - There is no chance that this is a hardware issue. Thinking about the possibility of replacing hardware might be interesting. Replacing individual hardware components  is not a realistic alternative. However replacing the router with a new device may, in fact, be your best alternative.

[majdi00011]

Thanks 

Here below version form router , could you please check and tell me 

Internet-Router#sh version
Cisco IOS Software, C2951 Software (C2951-UNIVERSALK9-M), Version 15.4(3)M3, RELEASE SOFTWARE (fc2)
Technical Support: http://www.cisco.com/techsupport
Copyright (c) 1986-2015 by Cisco Systems, Inc.
Compiled Fri 05-Jun-15 15:30 by prod_rel_team

ROM: System Bootstrap, Version 15.0(1r)M16, RELEASE SOFTWARE (fc1)

Internet-Router uptime is 47 minutes
System returned to ROM by power-on
System image file is "flash0:c2951-universalk9-mz.SPA.154-3.M3.bin"
Last reload type: Normal Reload
Last reload reason: power-on

This product contains cryptographic features and is subject to United
States and local country laws governing import, export, transfer and
use. Delivery of Cisco cryptographic products does not imply
third-party authority to import, export, distribute or use encryption.
Importers, exporters, distributors and users are responsible for
compliance with U.S. and local country laws. By using this product you
agree to comply with applicable laws and regulations. If you are unable
to comply with U.S. and local laws, return this product immediately.

A summary of U.S. laws governing Cisco cryptographic products may be found at:
http://www.cisco.com/wwl/export/crypto/tool/stqrg.html

If you require further assistance please contact us by sending email to
export@cisco.com.

Cisco CISCO2951/K9 (revision 1.1) with 487424K/36864K bytes of memory.
Processor board ID FGL21178225
3 Gigabit Ethernet interfaces
1 terminal line
1 Virtual Private Network (VPN) Module
DRAM configuration is 72 bits wide with parity enabled.
255K bytes of non-volatile configuration memory.
245448K bytes of ATA System CompactFlash 0 (Read/Write)

License Info:

License UDI:

-------------------------------------------------
Device# PID SN
-------------------------------------------------
*1 CISCO2951/K9 FGL21178225

Technology Package License Information for Module:'c2951'

------------------------------------------------------------------------
Technology Technology-package Technology-package
Current Type Next reboot
------------------------------------------------------------------------
ipbase ipbasek9 Permanent ipbasek9
security securityk9 Permanent securityk9
uc None None None
data None None None
NtwkEss None None None
CollabPro None None None

Configuration register is 0x2102

[Giuseppe Larosa]

Hello @majdi00011 ,

I have done a search in the bug tool for ISR 2951 with search keyword traceback there are 45 bugs listed but none of them applies to DNS server.

However, you likely have a software bug. The process involved is the DNS server so you should remove the line

ip dns server

and make an internal DNS server to run on a different device like a dedicated server or VM.

I would suggest this workaround if it is feasible.

Hope to help

Giuseppe

[MHM Cisco World]

It seem to me cache issue 
how to check ? clear ip dns cache <<- do this instead of restart if success I read somewhere there is command to config cache for DNS in router/SW  will check 
above is workaround it better to 

if you use DHCP and push router IP to host to use it as DNS server 
change it to any DNS external 

that it 

MHM