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My ISP seems to be blocking Port 53 if it is not connecting to one of its DNS servers. I was able to prove this through nslookup tests. Here are my tests:

Server:  UnKnown

Non-authoritative answer:
Addresses:  2404:6800:4008:c01::64


Pinging with 32 bytes of data:
Reply from bytes=32 time=1974ms TTL=40
Reply from bytes=32 time=1213ms TTL=40
Reply from bytes=32 time=165ms TTL=40
Reply from bytes=32 time=172ms TTL=40

Ping statistics for
    Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
    Minimum = 165ms, Maximum = 1974ms, Average = 881ms

DNS request timed out.
    timeout was 2 seconds.
Server:  UnKnown

DNS request timed out.
    timeout was 2 seconds.
DNS request timed out.
    timeout was 2 seconds.
DNS request timed out.
    timeout was 2 seconds.
DNS request timed out.
    timeout was 2 seconds.
*** Request to UnKnown timed-out

C:\Users\admin>tracert -d

Tracing route to over a maximum of 30 hops

  1     2 ms     2 ms     2 ms
  2   132 ms   407 ms   139 ms
  3   111 ms   156 ms   127 ms
  4   121 ms   136 ms   146 ms
  5   129 ms   137 ms   139 ms
  6   141 ms   151 ms   155 ms
  7   126 ms   137 ms   138 ms
  8   129 ms   139 ms   138 ms
  9   133 ms   138 ms   138 ms
 10   130 ms   137 ms   138 ms
 11   233 ms   137 ms   137 ms
 12     *        *        *     Request timed out.
 13     *        *        *     Request timed out.
 14     *        *        *     Request timed out.
 15     *        *        *     Request timed out.
 16     *        *        *     Request timed out.
 17   201 ms   219 ms   179 ms
 18     *        *        *     Request timed out.
 19     *        *        *     Request timed out.
 20     *        *        *     Request timed out.
 21     *        *        *     Request timed out.
 22   148 ms   157 ms   158 ms

Trace complete.

My ISP's DNS servers are slow and intermittent. Is there a way to override this? Is it possible to maybe set a DNS server that runs on a different port? Are public DNS servers like OpenDNS and Google Public DNS running these services on other ports?

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Can you show the DNS configuration in TCP/IP4 of network adapter please – grvpanchal May 25 '13 at 18:37
I think the best solution to this problem is to call your ISP and tell them to unblock it. If they don't, chew them out and switch ISPs. – Tanner Faulkner May 25 '13 at 19:46
up vote 4 down vote accepted

First, let me state that if your ISP is doing this then they're not really providing true Internet connectivity. It is not something appropriate for an ISP to do. They should fix it.

That being said, you can technically use a recursive resolver on a port other than 53, but it is not straightforward. There is no way to configure a nameserver in /etc/resolv.conf using a port other than 53, so you have to use some kind of hack such as DNAT to divert your local DNS queries to a port other than 53. And as for servers, you'll be hard pressed to find one out there that you can use and that listens on a port other than 53. This is partly because there is such bad support for specifying ports other than 53 on the client side that not many server operators find it useful to offer this.

So: you can set up your own recursive resolver somewhere outside of your ISP's network and which listens on a port other than 53, and use a hack like DNAT to sent your client queries to that server.

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OpenDNS accepts queries on both UDP and TCP 5353. – LawrenceC May 25 '13 at 22:52
@ultrasawblade You should have posted the comment above as an answer, I would have upvoted it, and many other people too, I bet. – MariusMatutiae Jun 3 '14 at 8:37

You could try using 'DNSCrypt'. This DNS resolver sends encrypted dns requests. And when DNSCrypt can't do it over port 53, it uses port 443.

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