From: Glenn (ggoldie@lineone.net)
Date: Fri Oct 10 2003 - 07:04:56 GMT-3
Hello everyone,
There is a difference between the global configuration cmd "ip
domain-lookup" and the line configuration cmd "domain-lookup" that John
is asking about. In the following examples I am connected to the console
port, however the same applies to the vty lines and presumably others (tty).
I start off with global "no ip domain-lookup" configured.
-----
Router#ping cisco.com
Translating "cisco.com"
% Unrecognized host or address, or protocol not running.
Router#conf t
Enter configuration commands, one per line. End with CNTL/Z.
Router(config)#ip domain-lookup
Router(config)#exit
Router#ping cisco.com
Translating "cisco.com"...domain server (212.142.28.66) [OK]
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 198.133.219.25, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 180/214/272 ms
Router#
Router#
------
Now an example of what the line configuration cmd "no domain-lookup"
does. Take note of the "show terminal" output before and after the cmd
is entered.
Router#
Router#show terminal
Line 0, Location: "", Type: ""
Length: 24 lines, Width: 80 columns
Status: PSI Enabled, Ready, Active, Automore On
Capabilities: none
Modem state: Ready
Special Chars: Escape Hold Stop Start Disconnect Activation
^^x none - - none
Timeouts: Idle EXEC Idle Session Modem Answer Session Dispatch
00:10:00 never none not set
Idle Session Disconnect Warning
never
Login-sequence User Response
00:00:30
Autoselect Initial Wait
not set
Modem type is unknown.
Session limit is not set.
Time since activation: 00:10:28
Editing is enabled.
History is enabled, history size is 10.
DNS resolution in show commands is enabled <--- TAKE NOTE
Full user help is disabled
Allowed input transports are none.
Allowed output transports are pad telnet rlogin.
Preferred transport is telnet.
No output characters are padded
No special data dispatching characters
Router#
Router#
Router#conf t
Enter configuration commands, one per line. End with CNTL/Z.
Router(config)#line con 0
Router(config-line)#no dom
Router(config-line)#no domain-lookup
Router(config-line)#exit
Router(config)#exit
Router#
Router#
Router#show term
Line 0, Location: "", Type: ""
Length: 24 lines, Width: 80 columns
Status: PSI Enabled, Ready, Active, Automore On
Capabilities: none
Modem state: Ready
Special Chars: Escape Hold Stop Start Disconnect Activation
^^x none - - none
Timeouts: Idle EXEC Idle Session Modem Answer Session Dispatch
00:10:00 never none not set
Idle Session Disconnect Warning
never
Login-sequence User Response
00:00:30
Autoselect Initial Wait
not set
Modem type is unknown.
Session limit is not set.
Time since activation: 00:11:33
Editing is enabled.
History is enabled, history size is 10.
DNS resolution in show commands is disabled <--- THIS HAS CHANGED
Full user help is disabled
Allowed input transports are none.
Allowed output transports are pad telnet rlogin.
Preferred transport is telnet.
No output characters are padded
No special data dispatching characters
Router#
-----
Host names that have previously been looked up are cached in router
memory so I will clear the dns cache in the router so we can be 100%
sure about what we are seeing.
Router#
Router#show host
Default domain is not set
Name/address lookup uses domain service
Name servers are 212.142.28.66
Host Port Flags Age Type Address(es)
cisco.com None (temp, OK) 0 IP 198.133.219.25
<--- THIS WAS FROM OUR ORIGINAL PING TEST ABOVE
Router#clear host *
Router#show host
Default domain is not set
Name/address lookup uses domain service
Name servers are 212.142.28.66
Host Port Flags Age Type Address(es)
Router#
-----
Okay, the cache is emptied.
Router#ping cisco.com
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 198.133.219.25, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 180/203/236 ms
Router#
-----
You can see from this 2nd ping that the global ip domain-lookup process
still works, even though we have configured the line config cmd to
disable domain lookups.
Router#traceroute cisco.com
Type escape sequence to abort.
Tracing the route to cisco.com (198.133.219.25)
1 192.168.99.100 4 msec 0 msec 4 msec
2 62.163.53.193 24 msec 24 msec 28 msec
3 212.142.27.185 28 msec 20 msec 24 msec
4 212.142.32.2 24 msec 32 msec 72 msec
5 212.142.32.44 24 msec 24 msec 28 msec
6 213.46.161.53 32 msec 52 msec 32 msec
7 213.46.161.193 28 msec 68 msec 68 msec
8 213.46.160.194 104 msec 112 msec 108 msec
9 65.59.192.9 120 msec 104 msec 160 msec
10 (cut short)
Router#
-----
Notice that even though global ip domain-lookup is enabled and verified
working, we aren't seeing any domain names in the traceroute output.
Next we can re-enable the line config cmd domain-lookup and see the
difference.
Router#
Router#conf t
Enter configuration commands, one per line. End with CNTL/Z.
Router(config)#line con 0
Router(config-line)#domain
Router(config-line)#domain-lookup
Router(config-line)#exit
Router(config)#exit
Router#
Router#
Router#traceroute cisco.com
Translating "cisco.com"...domain server (212.142.28.66) [OK]
Type escape sequence to abort.
Tracing the route to cisco.com (198.133.219.25)
1 192.168.99.100 4 msec 4 msec 4 msec
2 a53193.upc-a.chello.nl (62.163.53.193) 20 msec 32 msec 44 msec
3 atm11-0.ah00rt03.brain.upc.nl (212.142.27.185) 80 msec 40 msec 24 msec
4 srp0-0.am00rt02.brain.upc.nl (212.142.32.2) 28 msec 76 msec 44 msec
5 srp0-0.am00rt06.brain.upc.nl (212.142.32.44) 24 msec 28 msec 48 msec
6 nl-ams01a-ra1-so-0-0-3.aorta.net (213.46.161.53) 52 msec 24 msec 56 msec
7 nl-ams01a-rd1-pos-3-0.aorta.net (213.46.161.193) 56 msec 60 msec 28 msec
8 us-nyc01a-rd1-pos-0-0.aorta.net (213.46.160.194) 124 msec 108 msec
172 msec
9 65.59.192.9 120 msec 220 msec 228 msec
10 ge-0-3-0.bbr2.NewYork1.level3.net (209.247.9.209) 128 msec 104 msec
112 msec
11 so-0-0-0.mp1.SanJose1.level3.net (64.159.1.133) 196 msec 252 msec
240 msec
12
Router#
-----
It pretty much explains itself now. The show terminal command gave it away.
There are probably other examples but traceroute was the first one I
tried. Apologies if the formatting gets all screwed up.
Regards,
Glenn.
John Tafasi wrote:
>Hi Group,
>
>I entered the following commands on my terminal server.
>
>TServer(config)#line vty 0 181
>TServer(config-line)#no doma
>TServer(config-line)#no domain-lookup
>TServer(config-line)#end
>
>What show commands can I use to test this configuration?
>
>
>Thanks
>
>John Tafasi
>
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This archive was generated by hypermail 2.1.4 : Mon Nov 24 2003 - 07:53:00 GMT-3