Fixed IP addresses: which DNS should I use?

I've just set up a small home network in which I'm using FIXED IP addresses for the devices on the network. These devices are various computers and a server/printer. The ADSL router I'm using is the Billion 7800N and I'm using it with its DHCP server deliberately turned off. Which DNS server address should I be using in the TCP/IP settings of each device? The network-side IP address of the router, or my ISP's DNS address? Can either be used, as both seem to work?

Is 'DNS forwarding', a term I've sometimes heard in the context of routers, somehow involved with this? Are there any security implications for the choice of DNS?

use google dns servers as a starter

google for the addresses

I would tend to recommend using the router as a DNS server as it should be able to do a little bit of caching for the devices on your network and also it will be obtaining its own DNS from your ISP which also, hopefully, should be the optimal DNS server for your connection.

I would ping your ISP's DNS servers and the servers of any others you are considering,and use the ones with the lowest pings.

It depends on what you want, and what matters to you.

using your router as the DNS allows you to change all the DNS resolvers for your network in one place (The router is simply acting as a DNS proxy for which ever DNS resolvers it has setup. Depending on it's complexity it may be acting as a caching DNS proxy as Pipexer suggests.

Given that you have chosen to go to the trouble of setting static IP addresses and disabling the DHCP server on the router, I'm going to go out on a limb and suggest that perhaps that isn't one of your primary concerns.

You could use your ISP's DNS servers. There is no reason this would not work fine. Although given that David Cameron's porn filters, from what I am aware of, are largely DNS based filters set up by the larger ISPs you may decide to use alternative DNS servers.

Google offer a set of free DNS servers to anyone who wants to use them. As do OpenDNS, and a number of other groups. Some free DNS services (including openDNS) hijack incorrect DNS queries to serve up pages with advertising on them (as far as I am aware Google do not do this, but I have never actually used them).

You could also (if you have the inclination) set up a caching DNS resolver for your network. This would need some form of constantly running computer able to run a DNS server program. Bind is a common such peice of software for *nix based operating systems, and I have read of people setting up DNS servers on RasberryPI computers, for a small network the resources required for a DNS servers are very slight. However if you go down this line it is worth pointing out that some ISP's block outbound DNS traffic that is not bound for their own DNS servers (I know that Virgin Media are one such ISP).

Essentially you can use any DNS server that works for you, and meets your requirements.

And on to your final question, you need to be aware that the DNS servers you use can read every domain you lookup, which could be a privacy risk, and you need to trust the results your DNS provider returns, because dodgy DNS servers (either malicious or compromised servers) can send you to dodgy sites that appear otherwise perfectly legitamate, and you would have no way to tell other than querying a different DNS provider.

So what do you want, and what are you willing to invest?

(personally I run a copy of Bind on a linux server that I have running anyway)

In reply to a post by meditator:

Which DNS server address should I be using in the TCP/IP settings of each device? The network-side IP address of the router, or my ISP's DNS address?

Makes no odds. It's just of matter of ease for you of changing your DNS in future. By using the IP of the router in the TCP/IP paras, or better still letting all the devices 'Obtain DNS Auto', you only need change DNS in 1 central place, the router.

Ah, are you (and the other respondents) understanding my situation fully? The configuring of the DNS is being done by me in the TCP/IP area of the Network settings of the two computers, and only there. As far as I'm aware and apart from the fixed addresses of the computers/devices themselves, that's all you need to do. But I'm kinda getting the feeling that maybe there's something in the router itself that I also need to reconfigure. Is that so? What's thrown me has been "you only need change DNS in one central place, the router". The only change I've made in the router is to take it out of DHCP mode, which of course I don't need any longer and which I gather can sometimes lead to odd glitches in streaming scenarios if left on.

Yes. But the router is not going to be running a full recursive caching DNS server, and so it needs a forward resolver setup to be able to work as a DNS server. Set your DNS to the router, and you can change which recursive DNS server you actually use. (It will have those set automatically by your ISP, unless you change it manually).

In reply to a post by meditator:

Ah, are you (and the other respondents) understanding my situation fully?

I understand the situation and I think most of the other respondents do too. The issue is if you set manual DNS on all of those client machines, first of all, if you do need to change DNS settings you'll need to do it on multiple devices. Secondly, if you set the DNS manually to something on the internet then all of your clients are individually going to trouble a DNS server on the web (so let's say probably at least 20ms or so away) for every non-cached DNS record they need. There is a good chance most of your clients will hit the same webpages at frequent times (google, youtube, Microsoft, Windows Update, facebook, whatever).

Not only this, if your ISP is good, then their DNS server should be the best (or very near to the best) external DNS server for your devices, because it is doing a good amount of caching and should respond in the fastest time as it will be in your ISPs network (so very few hops away).

Your router will obtain the ISPs DNS servers automatically during its own DHCP process and therefore this will always be kept up to date with the latest DNS severs your ISP is using.

By setting the clients to ask your router as the DNS server, your router will be asking your ISP DNS server for the DNS query on behalf of your clients, however, it will probably be doing some caching itsself, so while in theory asking your router to ask your ISP (rather than just asking your ISP) may introduce a very minimal amount of latency (maybe 1-2ms tops), the caching means that if your router has already resolved the record for other devices on your network and has them cached, when the next device on your network comes along and asks for the record, it takes 1-2ms (to ask your router), rather than that 20ms to go and ask your ISP.

Even if your router does not do caching, then the added 1-2ms is worth putting up with because remember the router is automatically updated with the latest IP addresses for your ISP DNS servers and will prevent the situation occurring where your ISP changes the IP and you suddenly find web pages not working and you have to go round changing the settings manually.

The best is to have an actual DNS server running BIND or whatever in your house (again, using the ISP DNS as a forwarder) but we are going to presume you don't have a dedicated server, therefore, the router is best served as the DNS server for devices on your network.

All this theory completely breaks down if your ISPs DNS servers are carp, but then if your ISP is running carp DNS servers then they are probably a carp ISP and so all is lost anyway. It also breaks down if your router is particularly rubbish at acting as a DNS server/proxy, but this is quite uncommon.

By the way the comment about glitches in steaming and DHCP makes absolutely no sense at all, I would advise leaving DHCP turned on and setting reservations if you need to. If DHCP on your router is known to cause glitches in streaming, buy a better router, or quite like above with DNS, run a dedicated DHCP server

Edited by Pipexer (Sat 15-Mar-14 13:52:02)

In reply to a post by meditator:

The configuring of the DNS is being done by me in the TCP/IP area of the Network settings of the two computers, and only there.

Yes, I realise that you are talking about the TCP/IP properties of the Network Connections (or equiv.) of your various PCs.

I am just pointing out that you can choose where you set your DNS settings, for the external DNS you intend to use, either centrally in the router or dispersed in the various devices or indeed a mixture of them. From what you said it would be simplest and meet your requirements to set the DNS in the router and let the devices obtain the DNS addys auto. (i.e. from the router).

I also recommended that by setting DNS in the router, should you ever want to use diff DNSs, then your job will be easiest. It is not unheard of ISPs' DNSs playing up or going down for hours on end. In which case you would want to hurriedly swap to another set of DNSs; a public one like OpenDNS or Google DNS.