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Fallaback dns feature (LAN redundancy order)

Fallaback dns feature (LAN redundancy order)

Fallaback dns feature (LAN redundancy order)
Fallaback dns feature (LAN redundancy order)
Yesterday - last edited 10 hours ago
Tags: #Controller #DNS
Model: OC300  
Hardware Version: V1
Firmware Version: V1.6_1.31.10

Good morning and Merry Christmas to everyone,

 

I looked around and ddin't see any posts related to my topic, either on the controller user manual not the forums. I would like to know if there is a setting for fallback dns, and what/how is the working order, ie, 1) LAN DNS (1st IP and if not working then the 2nd IP will be used (LAN redunduncy), if not then 2) WAN DNS, if not then external DNS server, etc. 

 

Thanks in advance

 

V/r

 

 

Luis

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Re:Fallaback dns feature (LAN redundancy order)-Solution
18 hours ago - last edited 10 hours ago

@ceejaybassist DNS doesn't really work like that.  "Primary" and "Secondary" are imaginary terms as far as most OS go. 

 

The OS may try any of the DNS servers in its DNS settings based on an algorithm which varies by OS - for example, what happened the last time it did a DNS lookup, response times for either address etc.  It will use whatever response it gets first - including "no such hostname".  Yes, sometimes the first server listed is tried first, but that is not always the case.

 

I would not recommend using a mix of LAN and WAN DNS servers for any clients, unless you don't have any local DNS records resolving to local addresses.  And if you are doing any kind of security or ad-blocking via DNS don't expect it to work if you set a "fallback" DNS server that is configured differently.

 

Set all my local clients to use only a LAN DNS, and then those LAN DNS servers use public DNS servers to resolve anything they can't resolve locally.  If you are worried about redundancy you need multiple LAN DNS servers.

 

You can also set more than two DNS server addresses to use in most OS either locally or via DHCP, which again aren't always used in the order they are entered.

 

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#3
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Re:Fallaback dns feature (LAN redundancy order)-Solution
14 hours ago - last edited 10 hours ago

  @Antoni777 

 

Its actually possible to set up to a maximum of 4 DNS resolvers if you have an omada gateway and set the DNS Proxy to use DoT, then point all LAN clients DNS to the IP of the gateway on whatever vlan they use

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Re:Fallaback dns feature (LAN redundancy order)
Yesterday

  @Antoni777

There is the primary and secondary DNS servers in the LAN settings.

Though, I think, these are not "true" fail-over, because both of them are still querying your requests whenever you visit a website.

But if the primary goes down, the DNS requests will automatically be forwarded to the secondary.

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Re:Fallaback dns feature (LAN redundancy order)-Solution
18 hours ago - last edited 10 hours ago

@ceejaybassist DNS doesn't really work like that.  "Primary" and "Secondary" are imaginary terms as far as most OS go. 

 

The OS may try any of the DNS servers in its DNS settings based on an algorithm which varies by OS - for example, what happened the last time it did a DNS lookup, response times for either address etc.  It will use whatever response it gets first - including "no such hostname".  Yes, sometimes the first server listed is tried first, but that is not always the case.

 

I would not recommend using a mix of LAN and WAN DNS servers for any clients, unless you don't have any local DNS records resolving to local addresses.  And if you are doing any kind of security or ad-blocking via DNS don't expect it to work if you set a "fallback" DNS server that is configured differently.

 

Set all my local clients to use only a LAN DNS, and then those LAN DNS servers use public DNS servers to resolve anything they can't resolve locally.  If you are worried about redundancy you need multiple LAN DNS servers.

 

You can also set more than two DNS server addresses to use in most OS either locally or via DHCP, which again aren't always used in the order they are entered.

 

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#3
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Re:Fallaback dns feature (LAN redundancy order)-Solution
14 hours ago - last edited 10 hours ago

  @Antoni777 

 

Its actually possible to set up to a maximum of 4 DNS resolvers if you have an omada gateway and set the DNS Proxy to use DoT, then point all LAN clients DNS to the IP of the gateway on whatever vlan they use

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#4
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Re:Fallaback dns feature (LAN redundancy order)
14 hours ago

  @Antoni777 Good afternoon,

 

Thank you all for clarifying this for me. I'll be using an a filtering dns, but wanted to know what was possible, since I want to have redundancy in the even the private DNS server goes down. I wanted to see what others may suggest. I was thinkering with NEXTDNS as i want to prevent users from reaching certian sites. In summary, both DNS IPs need to be configured the same or the results will vary. This is a good question: does adding 127.0.0.1 to the second IP field will use the DNS DoH confgured servers?

 

V/r

 

Luis

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