Change DNS servers CISCO 1721

[vttech]

I need to change the DNS servers on a Cisco 1721 router
I figured that I have to attached a serial cable and telnet into the router to change the setting.

I have never configured a Cisco router and was looking for a clean step by step tutorial on how to change the DNS settings.

Thanks

Newbie in search of knowledge

 

[burtsbees]

Do you mean for the router to use, or for the router to give out in a dhcp config? This is for the router's dns...

router>en
router#conf t
router(config)#ip name-server x.x.x.x

Of course, x.x.x.x will be replaced by the IP address of the dns server you need.

router(config)#exit
router#copy run start

Also, you can console into the router with a console (rollover RJ45-to-db9) cable, using HyperTerminal, and all the default settings, on COM1.

Burt

 

[vttech]

I am using hyperterminal but I can't see anything on the screen that I type?

So I hit enter and get

User Access Verification

Password:


I attempt to enter the password but nothing appears on the screen. I am using a spare router to test. Any ideas what's going on?



Newbie in search of knowledge

 

[burtsbees]

Wrong password, maybe?
You will not see any output when entering the password, just like in a UNIX box.
Here is the process for password recovery---turn the router off, then back on---within 30 seconds, send a break(either ctrl-break, or shift-break), and you should come up with
rommon1>
then you type
rommon1>confreg 2142
rommon2>reset
The router reboots with the default config. When it comes up, answer no to the first question, yes to the second. Then you will be at
router>
then type
router>en
router#copy start run
router#conf t
router(config)#line con 0
router(config-line)#password whatever
router(config-line)#login
router(config-line)#exit
router(config)#enable password whatever
router(config)#enable secret cisco
router(config)#config-register 2102
router(config)#exit
router#copy run start
enter twice
router#reload

Your password for the console will be "whatever", and when you type
router>en
then password will be "cisco"

Burt

 

[burtsbees]

I forgot---you will need a password on line vty 0 4 in order to telnet to it, and an IP address (obviously) to telnet to.

Burt