Why does our Azure server respond to port 53 ?

Question

Why does our Azure server respond to port 53 ?

SilvaPaulaD 56

We ran a test and found our Azure hosted website listens to port 53. Does anyone know why and how it can be changed?

Anonymous

2022-12-16T16:10:00.01+00:00

Port 53 is Domain Name (DNS) service and should not be changed.

--please don't forget to upvote and Accept as answer if the reply is helpful--
SilvaPaulaD 56 Reputation points

2022-12-16T16:25:14.753+00:00

Why should it remain open?
Anonymous

2022-12-16T16:29:13.103+00:00

DNS maps ip addresses with fully qualified domain names. Without it many things will be broken. However you could consider this one.
https://support.microsoft.com/en-us/topic/how-to-disable-inbound-udp-for-azure-services-a853b461-a8b7-2951-ab3a-c7b818ffd0b0

--please don't forget to upvote and Accept as answer if the reply is helpful--
Anonymous

2022-12-17T14:06:18.19+00:00

Just checking if there's any progress or updates?

--please don't forget to upvote and Accept as answer if the reply is helpful--
SilvaPaulaD 56 Reputation points

2022-12-18T23:58:14.923+00:00

why should that port remain open?
Anonymous

2022-12-19T00:25:06.95+00:00

Did you see my answer above?
Anonymous

2022-12-19T14:01:06.43+00:00

Just checking if there's any progress or updates?

--please don't forget to upvote and Accept as answer if the reply is helpful--
SilvaPaulaD 56 Reputation points

2022-12-19T14:24:31.173+00:00

I read the article you suggested, and I am still a bit confuse as where the restriction should happen. I only use Azure to host my website but my DNS is a different provider (no Azure) Do you where the port should be close. I am sorry if my question is very silly?
Anonymous

2022-12-19T14:45:38.03+00:00

Ok, my bad, that one doesn't really apply. Something here could help.
https://learn.microsoft.com/en-us/azure/virtual-network/virtual-networks-name-resolution-for-vms-and-role-instances#web-apps

1 answer

Your answer

Anonymous

2022-12-16T16:10:00.01+00:00

Port 53 is Domain Name (DNS) service and should not be changed.

--please don't forget to upvote and Accept as answer if the reply is helpful--
SilvaPaulaD 56 Reputation points

2022-12-16T16:25:14.753+00:00

Why should it remain open?
Anonymous

2022-12-16T16:29:13.103+00:00

DNS maps ip addresses with fully qualified domain names. Without it many things will be broken. However you could consider this one.
https://support.microsoft.com/en-us/topic/how-to-disable-inbound-udp-for-azure-services-a853b461-a8b7-2951-ab3a-c7b818ffd0b0

--please don't forget to upvote and Accept as answer if the reply is helpful--
Anonymous

2022-12-17T14:06:18.19+00:00

Just checking if there's any progress or updates?

--please don't forget to upvote and Accept as answer if the reply is helpful--
SilvaPaulaD 56 Reputation points

2022-12-18T23:58:14.923+00:00

why should that port remain open?
Anonymous

2022-12-19T00:25:06.95+00:00

Did you see my answer above?
Anonymous

2022-12-19T14:01:06.43+00:00

Just checking if there's any progress or updates?

--please don't forget to upvote and Accept as answer if the reply is helpful--
SilvaPaulaD 56 Reputation points

2022-12-19T14:24:31.173+00:00

I read the article you suggested, and I am still a bit confuse as where the restriction should happen. I only use Azure to host my website but my DNS is a different provider (no Azure) Do you where the port should be close. I am sorry if my question is very silly?
Anonymous

2022-12-19T14:45:38.03+00:00

Ok, my bad, that one doesn't really apply. Something here could help.
https://learn.microsoft.com/en-us/azure/virtual-network/virtual-networks-name-resolution-for-vms-and-role-instances#web-apps

Answer 1

Hello,

It is possible that port 53 is being used for DNS (Domain Name System) traffic on your Azure server. DNS is a network protocol that allows servers to resolve human-readable domain names (e.g. www.example.com) into machine-readable IP addresses, and vice versa. Port 53 is the default port used for DNS traffic.

If you do not want your Azure server to listen on port 53, you can disable the DNS service or reconfigure it to listen on a different port. Alternatively, you can use a firewall or network security group to block incoming traffic to port 53 on your Azure server.

It is also important to note that port 53 may be used by other services on your Azure server, such as DHCP (Dynamic Host Configuration Protocol) or WINS (Windows Internet Name Service). Disabling or reconfiguring these services may affect the functionality of your server.

I hope this helps.

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Why does our Azure server respond to port 53 ?

1 answer

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