DNS Settings - Cache size - mine is full and stays that way?

RouterOS Beginner Basics
1

Hello all -

Am running a PC-based Mikrotik box - 4 Ethernet interfaces, for various ISP/WISP functions/customers.

I have version 2.9.43. I have “allow remote requests” checked. I have the cache set to 10240, which is the maximum it can be.

I have a primary onsite DNS server, which I have listed in Primary DNS. Since I do not have a secondary, I have a server from OpenDNS in the secondary.

My cache used stays very near or at 10240 all the time. TTL is set to 1 day.

Is this a problem or not?

Other notes: I am using DHCP for my wireless customers. I am passing the same 2 DNS servers to each of them.

Can I use the Mikrotik box as the secondary (or even the primary) to get faster throughput? Is this advisable or not? If so, do I put in the DHCP DNS server slot and also in the main Mikrotik DNS server slot?

I can give more details if needed. Thanks.

J

2

You haven’t really mentioned what problems you are experiencing. Can you post a simple network diagram please?

3

I just didn’t know if this was normal or not. It “seems” to be running fine.

Here is a diagram of my layout:

Ethernet0 - to Ethernet switch (to Cisco Gateway router & Primary DNS sever)
Ethernet1 - to Wireless PTP
Ethernet2 - to wireless PTP (uses DHCP/NAT)
Ethernet3 - to office network (uses DHCP/NAT)

I was just curious if I had my DNS settings the best way.

4

Upgrade to at least 2.9.51

5

Hi ;
i am using pc for MT OS 3.6 L4 .
i connect two internet modems to the server and i was passing many DNS servers to users .
then i made the MT as DNS server and put two dns servers in the / ip dns setting and in the dhcp server i repeat them and each client get the following :
DNS server :
192.168.190.1 " my MT ip " it include the dns servers 213,138.110.132 , 82.211.176.2 which it belong to my old ISP .
213,138.110.132
82.116.159.160 the primary DNS server to my internet modem 1
195.238.50.254 the primary DNS server to my internet modem 2
4.2.2.2
when i changed the series of the dns servers using 82.116.159.160 before 213.138.110.132 i start getting problems with nslookup
the dns not resolving the web sites as it was before .
now i only removed the dns server 192.168.190.1 from DHCP server setting , now it back normal but i now not using the MT as DNS server .
my question here , is it better to make the MT as DNS server ? , will it improve the service or not ?
any other information regarding setting DNS server for 3.6 will be welcomed .
with best regards .

6

Ahmed,

Please make separate topics/threads for seperate issues.

To answer your question, it sounds like you don’t have DNS server enabled correctly. Using Mikrotik as your DNS server works well if you cache DNS entries.

7

Hi ;
ok , i will post new topic tomorrow with some photos
with best regards

8

OK, I upgraded to 2.9.51 tonight. Rebooted - Cache is steadily filling up.

I’ll post any changes.

9

I guess I’m not seeing this as a problem. It sounds like it is working as it should - you just have a lot of DNS requests…

10

ok - but should I set the primary DNS to the Mikrotik itself? Wouldn’t that give a somewhat better performance since it will use its own cache instead of looking elsewhere?

Or leave it like it is?

I just want to get every drop of performance out of this box by every means possible.

Thank you.

Is there any reason at all to upgrade to version 3.x? I am very pleased with it. No probs at all.

11

I’d wait a few months before upgrading. Where are you talking about setting the DNS settings exactly?

12

Ok for starters, I wouldn’t be referencing the OpenDNS as the secondary. If you only have one internal DNS server then use that, it will be fine. I think your Cisco is your default gateway? If so then this must be the only box that references an external DNS server. Then your internal DNS server uses the Cisco as it’s DNS server and then subsequently services the rest of the network. If you want to you can make the Mikrotik the secondary for the LAN so in the /ip,dns settings, you’ll reference you’re Cisco router’s address and then in your DHCP settings, you’ll give out the existing name server and mikrotik as DNS servers.

Hope this makes sense and that I have understood you completely.

13

Hi Hilton ;
i will post a new topic regarding DNS settings as JWCN asked me , wish you read it and comment on it .
with best regards .

14

“If so then this must be the only box that references an external DNS server”

Can you tell me why this is?

Thank you.

15

It’s just what has worked for me especially configuring a lot of windows servers. In other words, keep the DNS as efficient as possible.

16

ok, please tell me this about my Mikrotik setup: (Using Winbox)

In the IP-DNS-Settings-Primary DNS - Which should I put? The IP of the Mikrotik itself, the gateway router, or my inhouse primary DNS server?

What about the secondary on this same screen?

Then, in my IP-DHCP-Server- which should I put for Primary and secondary?

I want this to work as efficiently as possible, and use the Mikrotik DNS cache effectively.

If you think my setup is OK right now, then thats fine also.

17

What I’m saying is there’s no point referencing an external DNS server. You need to just use whatever internal server you have. So that’s either the one you have or you need to make the mikrotik a DNS server as well.

I assume your existing DNS server is one that dynamically updates internal clients and handles reverse lookup zones etc?

If so that’s good. I don’t think the Mikrotik can do this, someone else may need to correct me on this. So if you really need a secondary name server, then reference the mikrotik but I suspect this will only be for lookups.

Am I making sense?

18

Thank you for your input -

What I am asking is this: When my Mikrotik assigns an IP using DHCP server to a customer, should they get the Mikrotik itself or my inhouse DNS server as primary? Then should I also assign a secondary (in-house DNS or MT) or leave it blank?

I want to make efficient use of the MTs cache, so shouldn’t I reference it first? I am thinking that if it doesn’t find an answer in the cache than it will ask the second DNS server (if there is one that was referenced).

thank you again.

19

Assign the users the address of your internal DNS server. They only need one address. Remember the Mikrotik is only a resolving cache server so it wont do stuff like dynamic reverse entries etc.

If your internal DNS server is setup properly, then let that do all the work and leave your Mikrotik to do whatever it’s doing.