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Cisco Bug: CSCvt38276 - Time Required for Hostname Resolution is Excessive if Hostname cannot be Resolved

Last Modified

Jun 15, 2020

Products (1)

  • Cisco IOS

Known Affected Releases

16.9.4

Description (partial)

Symptom:
When some hostname is typed during enable mode of the router and enter is pressed. The "connect" feature in IOS tries to telnet into that host. The hostname resolution is required at this point. The router will try to resolve the hostname to ip address using the configured nameservers in the router. If the hostname resolution times out after not getting response from the nameserver, the next nameserver is tried until it tries all of the nameservers configured. The timeout is derived dynamically based on RTT per server from Polaris 16.1 onwards as mentioned in the following bug CSCvn47686.

The total timeout is longer if multiple nameservers are unable to resolve the hostname or if the nameservers are unreachable.

Router# hostname            

The same behavior is observed during pinging the hostname that nameservers cannot resolve.      

Router# ping hostname

Conditions:
The following commands are enabled on the router

ip domain lookup
ip nameserver  nameserver1_ip  nameserver2_ip
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