From: Tarun Pahuja (pahujat@gmail.com)
Date: Tue Nov 06 2007 - 21:01:32 ART
Bhaskar,
We could have a long discussion on this topic. My
recommendation to you is to simply use "no ip domain-lookup" to avoid
unnecessary DNS lookup. One command(no ip domain-lookup) tells the router
not to perform dns lookup and the other(transport preferred none) specifies
a search order when attempting to resolve names that might be valid for
multiple protocols. They might solve your purpose majority of the times, but
not always!
Here is an example where transport preferred none might give you a problem:
r3(config)#ip host aaa 20.20.20.20
r3(config)#no ip domain-lookup
r3#aaa
Translating "aaa"
Translating "aaa"
Trying aaa (20.20.20.20)... Open
r3#conf t
Enter configuration commands, one per line. End with CNTL/Z.
r3(config)#ip domain-lookup
r3(config)#line con 0
r3(config-line)#transport preferred none
r3(config-line)#end
r3#aaa
^
% Invalid input detected at '^' marker.
r3#
HTH,
Tarun
On 11/7/07, Bhaskar Sivanesan <bas_bharath@yahoo.com> wrote:
>
> HI Group
>
> Consider the following qtn.
>
> - Configure all routers to avoid unnecessary DNS lookups.
>
> Which could be the ideal solution is it "transport preferred none" or " no
> ip domain-lookup". Think "no ip domain-lookup" will disable DNS querying
> even for legitimate queries like "ping <hostname>" (i.e) even a
> necessary DNS lookup cannot be performed if "no ip domain-lookup" command
> is used. So I feel "transport preferred none" could be the right solution.
>
> Your views please....
>
> Thanks
> Bhaskar
>
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This archive was generated by hypermail 2.1.4 : Sat Dec 01 2007 - 06:37:28 ART