If you have error like this on your Cisco box :
or your traceroutes take ages :
According to cisco.com :
Your router can be configured to use DNS lookups if you wish to use the ping or traceroute commands with a host name rather than an IP address. Use these commands to do so:
| Command | Description |
|---|---|
| ip domain lookup | Enables DNS-based host name-to-address translation. This command is enabled by default. |
| ip name-server | Specifies the address of one or more name servers. |
| ip domain list | Defines a list of domains, each to be tried in turn. Note: If there is no domain list, the domain name that you specified with the ip domain-name global configuration command is used. If there is a domain list, the default domain name is not used. |
| ip domain name | Defines a default domain name that the Cisco IOS software uses to complete unqualified host names (names without a dotted-decimal domain name). Do not include the initial period that separates an unqualified name from the domain name. |
| ip ospf name-lookup | Configures Open Shortest Path First (OSPF) to look up DNS names for use in all OSPF show EXEC command displays. This feature makes it easier to identify a router because the router is displayed by name rather than by its router ID or neighbor ID. |
But if you don't want to wait forever when your console become active again all you have to do is disable DNS lookup on your box.
By default DNS lookup is enabled on Cisco platform which cause delays in traceroutes and in few other cases. You can simply disable it using command :
R7(config)# no ip domain-lookup
Off course first you need to log on to the "configure terminal" promt but at this stage I hope I don't have to explain this :)
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