The default DNS port is 53. You can view the dynamic port range on a computer that is running Windows Vista or Windows Server 2008 computer by using the following netsh commands:
-
netsh int ipv4 show dynamicport tcp -
netsh int ipv4 show dynamicport udp -
netsh int ipv6 show dynamicport tcp -
netsh int ipv6 show dynamicport udp
To comply with Internet Assigned Numbers Authority (IANA) recommendations, Microsoft has increased the dynamic client port range for outgoing connections in Windows Vista and in Windows Server 2008. The new default start port is 49152, and the default end port is 65535.
| Traffic Type | Source of Transmission | Source Port | Destination of Transmission | Destination Port |
| Queries from local DNS server | Local DNS server | A random port numbered 49152 or above | Any remote DNS server | 53 |
| Responses to local DNS server | Any remote DNS server | 53 | Local DNS server | A random port numbered 49152 or above |
| Queries from remote DNS server | Any remote DNS server | A random port numbered 49152 or above | Local DNS server | 53 |
| Responses to remote DNS server | Local DNS server | 53 | Any remote DNS server | A random port numbered 49152 or above |