Fixing TFTP Boot Error with No Service Config

300-410 By islever Editorial Last updated

Troubleshoot device management

Short answer

A Apply the 'no service config' command to disable the automatic TFTP configuration loading that causes the socket error during bootup.

Question

A network administrator is reloading a router and during the bootup, he is getting the error message “%Error opening tftp://255.255.255.255/network-confg (Socket error)”. What command need to be applied on Cisco Router to fix this issue.
  1. No service config Correct Answer
  2. Write erase reload
  3. Reload noconfirm
  4. Copy run start

Key Takeaways

The question tests knowledge of the 'service config' directive and its impact on the boot sequence, specifically how to prevent unnecessary TFTP attempts when no server is available.

Resolve the '%Error opening tftp://255.255.255.255/network-confg' boot error on Cisco routers by disabling automatic network configuration loading with the 'no service config' command.

Common mistake: Choosing 'Copy run start' is a common mistake because it saves the current configuration, but it fails to address the root cause: the router's persistent instruction to look for a config file on the network via TFTP.

Expert Analysis

The error message "%Error opening tftp://255.255.255.255/network-confg (Socket error)" indicates that the router is attempting to load its startup configuration from a TFTP server during the boot process. This behavior is triggered by the service config command, which instructs the IOS to attempt to load configuration files from a network location if they are not found locally or if the NVRAM is empty.

The most attractive but wrong approach might be to simply reload the router again (Reload noconfirm) or save the running configuration (Copy run start). While saving the running configuration ensures current settings are preserved in NVRAM, it does not stop the router from attempting the TFTP download on subsequent boots if the service config directive remains active. Similarly, reloading without addressing the underlying configuration directive will result in the same error message appearing again during the next boot cycle.

To permanently resolve this issue, the administrator must disable the automatic network loading feature. Entering global configuration mode and applying the no service config command removes this instruction. Once this command is applied, the router will ignore the TFTP request and proceed with booting using the local configuration stored in NVRAM (if present) or entering setup mode (if NVRAM is empty). Therefore, applying no service config is the definitive fix for preventing this specific socket error.

Official Reference

https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/configurations/configuration/os-15-mt-config-book/oct15/os-15-mt-config-book_chapter_010.html#id_69380

This link opens the official vendor documentation in a new tab.

Exam Strategy

When troubleshooting boot errors involving TFTP or network loading, always check the router's configuration directives first. Commands like 'service config' can force behaviors that conflict with the current network environment. Disabling these directives is often the key to resolving persistent boot-time errors rather than just retrying the operation.

Frequently Asked Questions

What does 'service config' do?

The 'service config' command tells the router to attempt to load configuration files from a TFTP server during the boot process if the local NVRAM configuration is missing or invalid.

How do I prevent the router from trying to load config via TFTP?

Enter global configuration mode and use the 'no service config' command to disable this automatic network loading behavior.

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Community Votes

A
100%

100% of anonymous learners picked answer A. Votes are pick records left by other test-takers — they are not the verified answer.

Discussion 4 contributions

Compiled from public community threads and reader submissions, lightly edited for clarity. Handles and vote tallies are shown as recorded, and comments reflect the views of individual contributors.

From public community threads 4

  1. mitosenoriko 👍 2
    What to do depends on the situation. A.Probably OK. B.Remote monitoring would be a big problem. C.Retry this problem D.Saving bad configurations?
  2. sayed_2908 👍 2
    Ans:A https://community.cisco.com/t5/networking-knowledge-base/the-router-continually-tries-to-load-a-configuration-from-the/ta-p/3131171
  3. Brand 👍 2
    C1-HUB(config)#no service ? compress-config Compress the nvram configuration file config TFTP load config files
  4. Rebeen.Ra 👍 1 Answered A
    If there is no TFTP server set up to supply configurations, the router produces the %Error opening tftp://255.255.255.255/network-config (Socket error) message. Entering global configuration mode and applying no service config disables this automatic network loading behavior.

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