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Various Questions

Hi, folks:

I have a few random questions:

1. Why use the ip host tftp or ftp server command? Whenever I need to download code to a box, i use the copy tftp command and enter the info as it is asked...why use this command now?

2. If the "no ip domain lookup" command is entered, is DNS disabled? If so, why do I see configs with a domain name and name server configured while also disabling DNS with the no ip domain lookup command?

3. If you have 3 3750s in a stack, do you have to configure global commands, like SNMP, logging, passwords, etc, for EACH switch in the stack or does the IOS interface present the CLI as being a singular entity?

4. Is changing the TCP synwait time to, say, 5 seconds, from the default 30 seconds, something that is done to prevent the build up of embryonic TCP connections to the router in the event of a DoS attack?

Thanks ahead of time for the answers..

Cisco Employee

Re: Various Questions


let me give it a try ...

A1) In some situations it might be handy to use a router as a TFTP or FTP server for files in the flash. Example: your connectivity to the TFTP server is broken or blocked by a firewall. You might want to keep IOS versions for neighboring routers in flash for emergency recovery.

A2) "no ip domain lookup" prevents DNS lookups for anything mistyped at the CLI. f.e. If you type "shw" instead of "show" the router would try to resolve the host "shw" by DNS to telnet to it. This can cause a delay in accessing CLI again until the DNS request is either resolved or timed out.

A3) The stack is configured like one device, i.e. configuring SNMP etc. once is enough.

A4) Yes, can be one reason of doing it.

Hope this helps! Please rate all posts.

Regards, Martin

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