ROKU 3 & DNS

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ROKU 3 & DNS

Postby SkipFire » Sat Apr 27, 2013 8:33 am

Roku 2 has a problem where it only uses the first DNS server specified by DHCP and if that is down it goes to some hardcoded external list even though the DHCP information returns 3 DNS servers. Will Roku 3 behave correctly and if the first DNS server is not available go to the second specified by DHCP, or will it also ignore and jump to outside DNS servers?
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Re: ROKU 3 & DNS

Postby JimDandySTX » Sat Apr 27, 2013 1:08 pm

In most cases you are better off setting your router to automatically use the DNS servers of your ISP. Why if you push this function back on your router it then has to use its resources and processing power to resolve name look ups. Most home routers don't have the processing power that an ISP's equipment has.

Also just because you run Benchmark now and find the three fastest DNS servers now that doesn't mean that in fifteen minutes the result will be the same. If the help desk of your ISP starts getting calls about slow DNS resolution they can quickly locate the problem and if necessary change their look up table. Are you going to check your choices everyday?

On the Roku Forum site I know one of the favorite recommendations if you are having problems with Netflix is change your DNS servers and I am sure it has helped some people but in my personal experience I have never seen a significant difference much less an improvement in speed, but then with just a 5Mbps connection I have had very few problems streaming Netflix even though I am at least 1,200 miles from the nearest server. Perhaps if I had problems I might believe that changing the the preferred DNS servers was useful.

I have had problems with DNS servers going off line and name resolution timing out, but there is no guarantee that the servers you select will be any more stable than the ones your ISP picks.
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Re: ROKU 3 & DNS

Postby SkipFire » Sat Apr 27, 2013 3:04 pm

Terrible answer. External DNS won't resolve internal resources, hence the need for internal DNS. And my router isn't delivering DNS results, those are delivered by the DNS servers that are specified by the DHCP servers. Failing over to external DNS causes my Roku to not have access to anything internal, which is 95% of what we use the Roku's for.

So again, will the Roku 3 ignore DHCP protocol and default to external DNS servers if the first DHCP specified DNS server is unavailable, or will it follow the DHCP and DNS spec and go to the second server specified by DHCP if the first is not available? For me, having the Roku default to external DNS if the first internal DNS specified is offline is a killer and I have not bought or recommended Roku since I ran into this problem. Every non-Roku device has no problem failing over to the second or third DNS servers specified by DHCP if necessary.
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Re: ROKU 3 & DNS

Postby philsoft » Sat Apr 27, 2013 3:05 pm

SkipFire wrote:Terrible answer.


That ought to get people to want to respond to you eh?
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Re: ROKU 3 & DNS

Postby SkipFire » Sat Apr 27, 2013 3:50 pm

Telling someone they are doing things the wrong way without any clue why they are doing it that way isn't helpful, and no part of the answer addressed my question.
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Re: ROKU 3 & DNS

Postby JimDandySTX » Sat Apr 27, 2013 5:26 pm

I guess I don't understand what your problem or question is.

The DHCP server on your network assigns private IP addresses to all devices connected to your LAN. Not all devices need to request a private IP as it can be assigned using the connecting device's software/firmware. The Roku can't do this so it requests a private IP on your network from your router or modem. The IP assigned is in whatever range the network's administrator setup.

DNS (Digital Name Server ) just translates the words you type in into a numerical address (www.google.com = 74.125.229.209 ). There are at least 4,800 DNS servers. Depending on how you have set up your network a DNS server will perform the lookup. You can specify if the lookup is done using a DNS server(s) specified on your router or by default the DNS servers selected by your ISP. You could also set up your own DNS server on your own network to handle DNS requests, but then it would be your problem to keep it up to date. Finally if you want to speed up your initial network connection by 7 - 45 ms then type in the IP you want directly in numerical form.

Since the DHCP is a function on your LAN, DNS is a function used only when connecting to the WAN and only needed to connect to external resource, and that most network attached devices including the Roku 3 don't handle either function so what protocol is the Roku violating when it does or doesn't do what most devices do? In your network how are DNS and DHCP interfering with each other?
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Re: ROKU 3 & DNS

Postby SkipFire » Sat Apr 27, 2013 5:54 pm

DNS is NOT only for external, DNS is also used to resolve internal resources in structured environments (not just little home routers). The stuff on the inside is resolved by DNS entries, though they are private DNS entries not public DNS entries. My internal DNS servers can check external, but they are master for all of the internal DNS records as well. So, if I enter "mediaserver.domain.local" it resolves to 192.168.34.201, but if you try it on an external DNS server it just says host not found. This is very common for places that have servers such as geeks' homes, small businesses, large businesses, schools, basically anything but homes using the their cable or DSL modem or WAP for everything.

My DHCP environment has the IPs for DNS1, DNS2, and DNS3 specified as DNS servers; but if DNS1 is not available the Roku defaults to outside servers that can't resolve the internal servers where the content is, but if it obeyed the spec then it would go to DNS2 if DNS1 does not respond. If DNS1 and DNS2 don't respond it would go to DNS3, if all three are not available it would then fail, though I wouldn't mind if the Roku failed over to hardcoded DNS entries at that point.

If you ask why I don't just hard-code IPs of the media servers, it is because there are a large number that are DNS load balanced and support automatic fail-over. The environment is setup to support any system going down and having no visible impact, but the Roku's non-standard implementation of using only the first specified DNS entry provided by DHCP creates a single-point of failure that doesn't exist in the infrastructure.
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Re: ROKU 3 & DNS

Postby JimDandySTX » Sat Apr 27, 2013 6:38 pm

Thank you for your explanation. Your network is above and beyond what 99.9% on this forum have or even could envision.

I understand your problem and I guess it comes down to the fact that when you take a inexpensive consumer product and put it into a sophisticated network situation it just isn't up to the challenge. When Roku designed the product i"m sure they had to cut a few corners and unfortunately you are the victim.

Good luck on finding a work around.
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Re: ROKU 3 & DNS

Postby Basil » Sat Apr 27, 2013 6:58 pm

SkipFire wrote:DNS is NOT only for external, DNS is also used to resolve internal resources in structured environments (not just little home routers). The stuff on the inside is resolved by DNS entries, though they are private DNS entries not public DNS entries. My internal DNS servers can check external, but they are master for all of the internal DNS records as well. So, if I enter "mediaserver.domain.local" it resolves to 192.168.34.201, but if you try it on an external DNS server it just says host not found. This is very common for places that have servers such as geeks' homes, small businesses, large businesses, schools, basically anything but homes using the their cable or DSL modem or WAP for everything.

My DHCP environment has the IPs for DNS1, DNS2, and DNS3 specified as DNS servers; but if DNS1 is not available the Roku defaults to outside servers that can't resolve the internal servers where the content is, but if it obeyed the spec then it would go to DNS2 if DNS1 does not respond. If DNS1 and DNS2 don't respond it would go to DNS3, if all three are not available it would then fail, though I wouldn't mind if the Roku failed over to hardcoded DNS entries at that point.

If you ask why I don't just hard-code IPs of the media servers, it is because there are a large number that are DNS load balanced and support automatic fail-over. The environment is setup to support any system going down and having no visible impact, but the Roku's non-standard implementation of using only the first specified DNS entry provided by DHCP creates a single-point of failure that doesn't exist in the infrastructure.

Terrible answer.
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Re: ROKU 3 & DNS

Postby gonzotek » Sat Apr 27, 2013 7:24 pm

SkipFire wrote:DNS is NOT only for external, DNS is also used to resolve internal resources in structured environments (not just little home routers). The stuff on the inside is resolved by DNS entries, though they are private DNS entries not public DNS entries. My internal DNS servers can check external, but they are master for all of the internal DNS records as well. So, if I enter "mediaserver.domain.local" it resolves to 192.168.34.201, but if you try it on an external DNS server it just says host not found. This is very common for places that have servers such as geeks' homes, small businesses, large businesses, schools, basically anything but homes using the their cable or DSL modem or WAP for everything.

My DHCP environment has the IPs for DNS1, DNS2, and DNS3 specified as DNS servers; but if DNS1 is not available the Roku defaults to outside servers that can't resolve the internal servers where the content is, but if it obeyed the spec then it would go to DNS2 if DNS1 does not respond. If DNS1 and DNS2 don't respond it would go to DNS3, if all three are not available it would then fail, though I wouldn't mind if the Roku failed over to hardcoded DNS entries at that point.

If you ask why I don't just hard-code IPs of the media servers, it is because there are a large number that are DNS load balanced and support automatic fail-over. The environment is setup to support any system going down and having no visible impact, but the Roku's non-standard implementation of using only the first specified DNS entry provided by DHCP creates a single-point of failure that doesn't exist in the infrastructure.
I understand what you're doing and why, and it all sounds like more or less the correct approach to how I'd do it. But I have to ask, why would your internal DNS1 server be unavailable so often? Shouldn't that, by and large, have a stable & long uptime? When it becomes unavailable, doesn't that add lag to all or at least many of your other devices' lookups as well?

Btw, I'm in agreement that the Roku should(but doesn't) respect multiple DNS entries, if specified in the DHCP info. I don't think that's changed with Roku 3 software, although I can't easily test it to verify.
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Re: ROKU 3 & DNS

Postby SkipFire » Sun Apr 28, 2013 4:58 am

DNS1 doesn't go down frequently, maybe one unexpected failure in the last year, plus occasional maintenance downtime. But I have noticed that during playback having DNS1 reboot can cause media playback on the Roku to fail and DNS1 is not involved beyond providing DNS services, so from what I am observing the Roku continuously requests DNS resolution during playback, I had figured it would open a connection and just keep requesting subsequent chunks,though I can understand why it would be done either way.
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Re: ROKU 3 & DNS

Postby JimDandySTX » Sun Apr 28, 2013 7:45 am

SkipFire wrote:DNS1 doesn't go down frequently, maybe one unexpected failure in the last year, plus occasional maintenance downtime. But I have noticed that during playback having DNS1 reboot can cause media playback on the Roku to fail and DNS1 is not involved beyond providing DNS services, so from what I am observing the Roku continuously requests DNS resolution during playback, I had figured it would open a connection and just keep requesting subsequent chunks,though I can understand why it would be done either way.


Just to satisfy my curiosity after our discussions yesterday I did a little reading on line re: Reverse DNS lookups.

http://lani78.wordpress.com/2012/07/22/ ... in-server/

According to one of the above article it is possible to setup/ control where DNS requests are forwarded if the primary internal DNS server fails or at least doesn't resolve a lookup.

Based on what is happening with your Roku are you saying that it is able to override the programming of your network and seek out its own DNS? Or is the problem that if your internal server fails and the request is forwarded correctly according to your rules and the request is for a private IP you will get the message not found?

Just curious.
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Re: ROKU 3 & DNS

Postby RokuMarkn » Sun Apr 28, 2013 7:54 am

SkipFire wrote:DNS1 doesn't go down frequently, maybe one unexpected failure in the last year, plus occasional maintenance downtime. But I have noticed that during playback having DNS1 reboot can cause media playback on the Roku to fail and DNS1 is not involved beyond providing DNS services, so from what I am observing the Roku continuously requests DNS resolution during playback, I had figured it would open a connection and just keep requesting subsequent chunks,though I can understand why it would be done either way.


That''s not the behavior I would expect, unless that DNS server is also your gateway. The Roku caches DNS lookups so it shouldn't lookup a particular IP address more than once until it falls out of the cache. However depending on the channel, it may be requesting new addresses during playback (ad servers, analytics servers, etc).

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Re: ROKU 3 & DNS

Postby SkipFire » Sun Apr 28, 2013 8:43 am

DNS1 is not my gateway, and I observe the issue with internal traffic so it would not be using the gateway anyway.
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Re: ROKU 3 & DNS

Postby SkipFire » Sun Apr 28, 2013 8:45 am

Jim - Roku only uses the first DNS server specified, after that it fails back to some hardcoded list (previously confirmed to me by Roku) of external DNS servers.
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