Configuring a cisco router using command line interface...
July 13, 2011 9:51 PM   Subscribe

Help me configure my CISCO 877 router...

I was able to make the ADSL connection successfully through the help of my Internet service provider using the Security Device Manager but my router is unable to find my DNS settings and upon finally testing the connection I get the error...

DNS configuration check has failed. No DNS Lookup has been configured. Configure the command 'ip domain-lookup' in the config mode on the router.

I have no idea how to access the config mode on my router or how to access the command line interface.

Could someone please help me out.

My primary DNS is and secondary DNS is

I have the console cable and I've enabled telnet on my Windows 7 but have no Idea how to make these changes.

I found a good website for the commands here (under Configure DNS, or disable DNS lookup), but I have no idea how to put them into the router.

Thanks so much guys in advance...
posted by Bacillus to Computers & Internet (10 answers total)
Response by poster: I also have my routers IOS.bin file which I have no idea on how to use.... which I think is meant to be used to access the command line interface.
posted by Bacillus at 9:54 PM on July 13, 2011

Response by poster: I found out I can get into the Telnet of the router through the SDM but all that comes up is it asks me for my username and password then all I see is...


but I'm trying to get the command line interface that says...

posted by Bacillus at 10:41 PM on July 13, 2011

Type "conf t", press enter, and that'll get you to config mode. When you're done make sure you type "wr mem" to save your changes. Depending on the router you may need to drop down to the regular # prompt by typing "exit" before doing the "wr mem".
posted by mikesch at 11:01 PM on July 13, 2011

On cisco routers, if you hit '?', it gives you a list of possible commands, and you can hit ? after every word you type to get more options. Think of it as a menu, where each word you take takes you further into menus.
posted by empath at 11:32 PM on July 13, 2011

Response by poster: Thanks for the help guys but with everything I tried I still couldn't get it to work.
posted by Bacillus at 1:44 AM on July 14, 2011

well ... looking on the internet it seems to be a cisco IOS router ... which is truly a PITA to configure if you don't know how.

Serious question ... have you considered getting a consumer-grade point-and-click config router?

But ... to answer the question, in config mode, the command is: ip name-server x.x.x.x
(and repeat for the secondary ... the config file is parsed in a step format and it knows that the 2nd instance of this command identifies the secondary DNS).

However ... this will only set up the router as a DNS client (which, in itself, is of very limited value ... why woul a router ever want to resolve names?) ... your connected PC will need to have its local DNS server set by either static config or DHCP ... so ... Are you asking the wrong question.

Is your actual question "how do I set up DHCP on a cisco 877 and provide DNS Server settings to the DHCP clients?"

Well ... you might want to look further on this posting: HERE
posted by jannw at 2:21 AM on July 14, 2011

(meant to say ... 4th last post in the link details setting up NAT and DHCP)
posted by jannw at 2:34 AM on July 14, 2011

and a quick intro to configuring Cisco IOS can be found here
posted by jannw at 2:35 AM on July 14, 2011

It looks like your router is set up to have the name "username". At that "username" prompt, type "show running config" (or it might be "show running-config"). Look at the output and see if your router's hostname is set to "username".

See, the Router> or Router# prompt will only be that on an unconfigured router. Once you have given it a hostname, the prompt will change to that. So if the hostname is "branch-office", your prompt will be branch-office>.

So you will probably want to change the router's hostname to the right name.

When you are at the ">" prompt, type "configure terminal", and the prompt will change to #. Then you can enter the commands to change the dns. This changes the running configuration, which is what the router is using right now to do its work. If you reboot, it will revert to the startup-config and your changes will be lost. So once you get it working properly, you need to copy the running config to the startup config.

This is either

copy running-config startup-config


copy system:running-config nvram:startup-config


copy system:running-config flash:startup-config

depending on the model.

IOS isn't easy.

I might suggest doing a factory reset and starting from scratch by running the "setup" command.
posted by gjc at 5:30 AM on July 14, 2011

Generally, if you didn't buy a Cisco because you needed something the Cisco does, you should not have a Cisco. Take it back and get a decent linksys, imo.
posted by empath at 12:02 PM on July 14, 2011

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