DNS Confusion. 300 series.

[Switchasaurus]

Dear Wise Forum Members. 

I'm not a complete and utter fresh out the box noob, whilst pretty much useless, I do understand DHCP vs Static, POE, I have LAN going with IP cameras and terminals etc, but this is all born out of practical investigation rather than formal training, yet I have hit my first problem I can't solve. I am sure I will need some conceptual back up in the futures, I have ambitions of a Pi Based PBX... (one step at a time) So I thought I would register and see if some help can be found.

My Question:

How do I setup a 300s Managed switch to distribute DNS provided from a domestic fibre connection modem. I turned off DHCP on the modem, nicely working on the cisco, all devices on LAN nicely, yet I am missing some concepts regarding how DNS fits into the LAN picture. 

I tried adding DNS entries including Google and the services providers. I also tried the modem gateway IP as a DNS entry incase that worked. 

I don't have nearly enough conceptual understanding of how this bit should work. 

Any pointers would be great. I asked a few people to help locally but their skills are weak: they advised me turn the DHCP back on the modem and forget out about it. I hate the admin interface on the domestic router: it is painful, requires constant restarts. 

Some direct advice or suggested reading/search terms all gratefully received. 

Many thanks

Switchasaurus 

[Dan Lukes]

Well, it seems to be true you don't know how the DNS work ;-)

DNS is sort of distributed database that provide data to clients. In most common case such database is used to convert host name to IP (e.g. you query the database for IP address stored for particular host name)..

Any DNS client (e.g. casual computer in most cases) wishing to ask DNS server needs to know IP address of a DNS server. Such address can be configured either by administrator (static) or delivered by other protocol (DHCP, for example). It's the only relationship between DNS and DHCP - DHCP may deliver address of a DNS server to the end device.

According DNS server's place in LAN picture - it's casual network server. Like WWW server, FTP server or so. It can be placed anywhere - either in the local network or may be outside. It will work as long as clients will know their IP address.

So your's computers can use any DNS server willing to respond their question. Address of such server needs to be configured either statically or via DHCP (as described above). In common case the DNS server provided by your ISP to you is used, you may use Google's DNS server 8.8.8.8 as well although I don't recommend to use them, and finally, you may arrange your's own DNS server.

Switch is not so common place to run own DNS server and as far as I know thus product line doesn't support DNS server running on them, so your switch will not distribute DNS to anyone - not counting the fact it will distribute packets carrying various data, including the DNS one, from a client to a server.

If I understand you issue correctly, you need to discover what DNS server should be configured on computers in your's local network. Well, it need to be address of a DNS server. I don't know if your's mode provide such server - if yes, then it's address is the one you are asking for. If not, then use IP address of DNS server provided by ISP.

Hope it help.

And yes, this topic doesn't fit this community. I will ask moderators to move it to more appropriate place.

[rosaho]

This discussion has been reposted from Cisco Small Business Support Community to the Cisco Cafe community.