Stopping Accidental Cisco IOS Domain Name Translation
02/27/2017 • 2 minute readI often switch between Cisco IOS and Bash so I absentmindedly type ls into a IOS prompt and have to wait 30 seconds on this error:
Translating “ls”…domain server (255.255.255.255)
% Unknown command or computer name, or unable to find computer address
To stop this, you can just press CTRL+Shift+6. But for more long-term fixes, see the options below:
Option 1: Stop router from starting connection without telnet keyword
router(config) #ip domain lookup
router(config-line)#line con 0
router(config-line)#transport preferred none
Option 2: Shorten TCP Connection Timeout
router(config) #ip tcp synwait-time 10
This isn’t preferable as it can affect things like handshakes for Multicast/BGP
Option 3: Disable Domain Lookup:
router(config) #no ip domain lookup
I hesitate to recommend this one as it might affect the 1% of sites that need it. Also it stops DNS load-balancing, which I need in enterprise environments. You can also disable per session Domain Lookup like so:
#terminal no domain-lookup