Domain Name Service Udp. 2 UDP is not reliable but reliability can added on application layer. Once the user types a domain name into their browser the users device creates a DNS query and sends it to a specialized web server called a DNS resolver.
The root name server can also contain some hostName to IP address mappings. Internet Connection FirewallInternet Connection Sharing. Enter the tcp-udp keyword if your service uses both TCP and UDP with the same port number for example DNS port53.
This is a list of TCP and UDP port numbers used by protocols of the Internet protocol suite for operation of network applications.
The DNS resolver matches the queried domain name to an IP address either by querying additional DNS servers or by checking its cache. As listed above by ignoring UDP ports known vulnerabilities may remain ignored to the user. Enter the tcp-udp keyword if your service uses both TCP and UDP with the same port number for example DNS port53. The client machine sends a request to the local name server which if root does not find the address in its database sends a request to the root name server which in turn will route the query to an intermediate or authoritative name server.