CCIE Pursuit Blog

January 19, 2008

Internetwork Expert Volume II: Lab 4 – Section 10

IP Services – 5 Points

10.1 DNS

A DNS entry has been incorrectly configured to point to 141.1.0.22.  You need to:

“Without applying this IP address to any interface, permit users to telnet to r2 using this DNS entry or IP address.”
“Do not use NAT to accomplish this task.”

So I need a way to route traffic for the DNS name “r2” to 150.1.2.2 rather than 141.1.0.22.

I knew how to do this task because I have used the “show ip alias” command many times to harvest IP  addresses for my ping scripts.

ip alias

r2(config)#ip alias 141.1.0.22 ?
  <0-65535>  IP port number

r2(config)#ip alias 141.1.0.22 23

r2#sh ip alias
Address Type             IP Address      Port
Interface                141.1.0.2
Alias                    141.1.0.22     23
Interface                141.1.25.2
Interface                141.1.123.2
Interface                150.1.2.2

r4#telnet 141.1.0.22
Trying 141.1.0.22 … Open

User Access Verification

Username: NOC  <-from earlier task
Password:

    NOC Options

    1          Ping r5’s loopback 0

    2          Ping r6’s loopback 0

    3          Trace to r5’s loopback 0

    4          Trace to r6’s loopback 0

    5          Quit (Access CLI)

10.2 Gateway Redundancy

Long winded way of saying configure HSRP.  🙂

The first subtask was well written in that it is pretty easy to get thrown off task if it confuses you.  I was initially wondering how I would get half of the clients to use one gateway and the other half to use the other.  A quick reread showed that I needn’t worry.

standby ip

Just make sure that you configure preempt.

r3#sh standby brief
                     P indicates configured to preempt.
                     |
Interface   Grp Prio P State    Active          Standby         Virtual IP
Fa0/1       36  110  P Active   local           141.1.36.6      141.1.36.1
Fa0/1       63  100    Standby  141.1.36.6      local           141.1.36.2

r6#sh stand brief
                     P indicates configured to preempt.
                     |
Interface   Grp Prio P State    Active          Standby         Virtual IP
Fa0/0       36  100    Standby  141.1.36.3      local           141.1.36.1
Fa0/0       63  110  P Active   local           unknown         141.1.36.2

This forum posting brings up an interesting point about this task violating the  “do not create additional IP addresses unless specified” rule:

10.2 Gateway Redundancy

10.3  Failure Message

“Configure r3 to display a “Host Failed” message of “Connection Unsuccessful” when a telnet session to r4’s loopback 0 interface fails.”

No idea.  I tried to find something in the Command Guide, but I did not have luck on my side.

I have never heard of this command before:

busy-message

To create a “host failed” message that displays when a connection fails, use the busy-message command in global configuration mode. To disable the “host failed” message from displaying on the specified host, use the no form of this command.

busy-message host-name d message d

r3(config)#busy-message r4 #
Enter TEXT message.  End with the character ‘#’.
Connection Unsuccessful#
Unable to set busy message for r4

You’ll need to configure ‘ip host’ for r4 in order for this to work:

r3(config)#ip host r4 150.1.4.4
r3(config)#busy-message r4 #
Enter TEXT message.  End with the character ‘#’.
Connection Unsuccessful#

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