DNS Issue Windows Server 2012

Question

I am trying to add a string to Ajax response in a selector.

function get_class_subject(class_id) {
  $.ajax({
    url: '<?php echo base_url(); ?>admin/get_class_subject/' + class_id,
    success: function(response) {
      jQuery('#subject_selector_holder').html(response);
      console.log('my message' + response);                
    }
  });
}

I am getting response as follows:

my message<option value="5">Moral Science</option>

What I need to get is adding <option value="100">Break</option> that is

my message<option value="5">Moral Science</option><option value="100">Break</option>

How can I achieve this?

Solution

So it worked fine with 8.8.8.8 as the original forwarder but not with your ISP's DNS servers?

That would seem to be the issue then, that your forwarders you have in place are causing slow DNS resolutions. You can easily confirm if DNS is causing this. Just use FileZilla and FTP into an FTP site via IP address (not FQDN) and then transfer a large file from that FTP site to you. If it runs at the right speed, then your issue is DNS resolution (and probably just your forwarders).

Comments

[kralyk]

odd...what happens if you change forwarders to something like 4.2.2.2 or 8.8.8.8?

[Doon]

So workstations have GW set as netopia router, but when DNS is set to WS2012 after a while their access gets slow? when it is slow. have you tried doing NSlookups to see if dns resolution is indeed taking a long time? but also this would only affect loading pages, etc. once it gets the answer, file downloads/etc should not be affected as they are not using DNS. The normal way I would set something up like this is disable DHCP in the router, enabled DHCP / DNS in the WS server, and set forwarders int the server to the upstream caches.

[Dhruvb14]

TheCleaner: so I initially had forwarders set to google's dns as you mentioned with ISP as fallback. This had worked for the last 6-7 months flawlessly. @Doon This is what does not make sense to me either since DNS is only used for lookup of IP and initial page load. However when running speedtest.net after clearing cache its 4-5Mbps and then after 10-20 minutes as mentioned it slows to about .1-.2. Now what is the part you mentioned about "set forwarders int the server to the upstream caches." this part i am not sure about.

[Doon]

(i am not windows guy). but AD needs to be the master DNS, and all workstations needs to use it else naming breaks, etc. also it seems to work better when the Domain is in control of everything(DNS/DHCP/etc...) So the router is just a router, disable DNS and DHCP on it, letting the windows server do those functions It just becomes the default gateway.. Then inside your windows server in the dns snap in, under actions-> properties you should have a forwarders tab, that you can use your ISP (or googles servers). This way local queries are local, but unknowns get forwarded and then cached)

[Doon]

but yeah the network slowdown after clearing DNS cache for things that aren't new connections is odd. How are you clearing the cache in the router? (or is the Server). And to be clear the router is the GW. Also are both your wan and lan connections plugged into the same switch/same vlan?

[Dhruvb14]

@Doon Here is a better map of the network link[/link] When clearing cache i'm using the windows DNS manager and rightclick on dns server and clear cache. Under my DHCP server should I set the default gateway to be the WS2012 so all data is routed through the WS2012? Thanks in advanced for your help

[Doon]

no don't set the GW to the Server, that is what I was making sure wasn't already in place. the router is the GW. Sorry I guess my it above was ambiguous. I meant the router is just the GW, let the server handle the rest. Have you tried to clear the cache in the middle of a slow speedtest and see if that changes the in process connection. if it does then I am totally stumped

[Doon]

also do you have the ability to sniff the traffic going towards the gateway to see if you have something that is eating up your bandwidth that you don't know about? Could be virus/bot or the like that is filling your uptream, thus slowing your down stream and perhaps flushing ths dns cache slows it down a bit (this is a WAG, but worth looking into all things being the same )

[Dhruvb14]

@doon yeah that is the way everything was setup (router is only the GW everything else going to WS2012). I am going to try to run wireshark in catch all traffic mode to see if something (virus/bot) is trying to eat up traffic. However the only thing running on the network when I was trouble shooting last night was my Mac, the WS2012 and PBX system which is running standalone PBX software (linux).

[Ed Fries]

Seems doubtful this is a DNS issue; more likely P2P, music/vid downloads, offsite backup and/or virus/bot. I would enable SNMP on the router, install PRTG on a local workstation and see how much traffic is flowing through the router. A firewall (or a managed switch, port mirroring & Wireshark) would be the solution to see where the traffic is coming from. Without that, since network seems small, watch PRTG, pull the network cables on 1/2 wkstns, keep doing this until the source(s) are narrowed down. Otherwise, have you confirmed w/ ISP that circuit is running fine w/ no errors?

[Michael Hampton]

Welcome to Server Fault. If you solved your own problem, please post it as an Answer and then accept it by clicking the check mark next to your own answer. This is not a forum, and so it's not necessary to put things such as "SOLVED" in the question title.

[CertainPerformance]

Did you try using string concatenation?

[Rory McCrossan]

Just append the HTML string, in the exact same way you already are in the console.log...?

[Dhruvb14]

I had it working fine with 8.8.8.8 as dns for 6-7 months no issues. About a week ago these issues arose. I changed dns to ISP thinking that was issue but it was not since the internet was very fast when i cleared dns cache from inside dns manager on WS2012. After a little bit of time (10-20 min) it becomes slow again.

[kralyk]

Can you try the FTP via IP test and see what bandwidth results you are getting? You need to start narrowing it down.

[Dhruvb14]

Ok so i solved the issue and this a new one. So the previous sysadmin had opened up the router to put a dedicated External IP on the server. With the new install there were no external services running on the machine(Email, webserver, etc)so i setup the DNS server with open modifications from outside since I assumed (My fault) that it was providing strictly internal dns functions. Well the domain started getting dns update requests on from tons of different places and it looks like that was causing slow down and thats why clearing cache worked for a bit. Removed static IP and it works now. :)