Problem with ISP-DNS-Servers

RouterOS General
1

Hello @ all,

as it would appear I have a problem with the DNS-server(s) of my ISP.

I use two connections ADSL and behind works a network for nearly 80 clients. Sometimes are the connections at www very slowly and if I make a traceroute there are some timeouts at this moment. But it is every time from another board and at another time. Other boards are working fine at the same time.
Now I would try to use other, free DNS-servers, because I think that my ISP “plays” with his DNS-servers. My connections are working with DHCP from the ISP.

My question:

Can I configure other DNS-server-IPs simply in the WINBOX by using >ip dns settings and it will work so?
Or is it better if I make an own DNS-server for example BIND and if so, how can I integrate this at a Mikrotikboard?

Regards

Uli

2

From the traceroute it doesn’t look like it is related to the DNS servers, rather to instability
of the link. Anyway, if you want to use a free DNS server you can simply put the IP address
of the DNS server in /ip dns settings.
Since you get connected to the internet using dhcp-client, remember to remove the option
“use peer dns” from the dhcp-client settings. That option would overwrite your settings every time
your dhcp-client gets a new lease.

3

Thank you for response, Caci99. I will do so.
What do you mean here ?

instability of the link

The timeouts are behind the gateway, somewhere at the www-routers, not at my network.

Regards

Uli

4

Instability of the link, I mean that the link drops connection. The connection is not stable, it keeps
disconnecting.
As you know, during a traceroute you execute ping to every router/server along the path (ICMP protocol),
it could be that some of those routers/server have been configured to drop any ICMP packet, thus
sometime giving you a false result of the connection.

5

Hmmm, all right, but if the traceroute (for examble to google.com) works exactly at the same time from 7 other Mikrotikboards in my network? All use the same gateway. This is what I do not understand.

Regards

Uli

6

… and another observation:

I am using 2 gateways fron Tel. Argentina and one from Copaco Paraguay. Normaly the trafic is more stabil and I habe more bandwidth with the connections of Argentina, but this error also happens only there. If I have the problem of timeouts and change the gateway to Copaco the error is away here.

What can it be? I´m perplexed. Anybody an idea?

Regards

Uli

7

i use googles dns

ip/dns

8.8.8.8
8.8.4.4

or punch it in on your adsl router & in ip/dns in winbox user your adsl routers ip

8

What do ICMP probes (ping/traceroute) timing out have to do with DNS?

9

Hello again,

What do ICMP probes (ping/traceroute) timing out have to do with DNS?

You are right, fewi, but I thought so and that´s why I tryed it. The timeouts are only at the gateway of one provider…

Well, I will check sometings more and open a new topic, if I do not found the reason.

But anyway, the fact with the DNS-servers is, that it only works, if I put the DNS-server-address at the computer or the first router at my home-network.
If I set the Mikrotiks in ip dns settings it ignors that and all other users are working always with the DNS-server of the provider.
Why?

Regards

Uli

10

What DNS server do you hand out to the users via DHCP? If you’re handing out the ISP DNS server that’s what clients will use.

You can force that the router be used as a DNS server by redirecting all DNS to it via NAT:

/ip firewall nat
add chain=dstnat protocol=udp dst-port=53 action=redirect
add chain=dstnat protocol=tcp dst-port=53 action=redirect
11

Yes, this solved the problem. Thank you for helping!