What's New in DNS Client
Updated: July 3, 2014
Applies To: Windows 8.1, Windows Server 2012 R2, Windows Server 2012, Windows 8
This topic provides information about new and changed functionality in the DNS Client service in Windows 8.1 and Windows 8.
In this topic:
In Windows 8.1, the DNS Client service offers enhanced support in the following areas.
Changes to the DNS Client service in Windows 8.1 are also present in computers running Windows Server 2012 R2. For more information, see What's New in DNS Server.
New or improved
DNS query adaptive timeout
This feature enables the timeout for DNS queries to adapt based on the time required for previous queries, reducing the timeout for most queries. Timeouts can also be increased for high-latency links, such as satellite links. Configuration of DNS timeouts is enabled on a per network interface basis, and can be optimized by Windows Store apps.
Instead of waiting for 1000ms before timing out a DNS query, the first timeout is adjusted to be between 25ms and 1000ms, based on past performance of the network.
DNS server non-responsive cache
Nonresponsive DNS servers are cached and periodically retried. This enables the DNS client to use the best available server consistently, and to spend less time waiting for unresponsive DNS servers.
DNS cache improvements
The DNS cache is improved to consolidate cache entries, enable more cache entries, and to permit caching of additional records.
DNS query coalescing
Multiple DNS queries for the same name are combined, resulting in only one DNS query. This optimizes client, network, and server resources.
Improvements are made to Software Quality Metrics (SQM) reporting for the DNS client. This information can be used to improve performance and reliability.
Events for name resolution
Event tracing for Windows (ETW) events are added to DNS logging. This feature will assist with troubleshooting DNS issues.
Parallelize A and AAAA queries
A and AAAA DNS queries are issued in parallel, saving time for interfaces that have both IPv6 and IPv4 addresses.
Per interface Winsock name resolution
This feature enables the GetAddrInfoEx() application programming interface (API) to issue a name query on a specific network interface.
Asynchronous Winsock name resolution
This feature enables the GetAddrInfoEx() API to issue asynchronous name resolution queries.
The DNS cache is now persistent across changes that occur on the same network, including address change notifications and sleep-resume-standby state transitions.
In Windows 8, the DNS Client service offers enhanced support in the following areas.
Changes to the DNS Client service in Windows 8 are also present in computers running Windows Server 2012. For more information, see What's New in DNS Server.
New or improved
Link-local multicast name resolution (LLMNR)
Outbound LLMNR queries are not sent to mobile broadband and VPN interfaces.
Network basic input/output system (NETBIOS)
Outbound NETBIOS queries are not sent to mobile broadband interfaces.
The LLMNR query timeout has been increased to 410 msec for the 1st retry and 410 msec for the 2nd retry. The total timeout value is now 820 msec instead of 300 msec. This change is to solve a problem with computers in power saving mode. LLMNR and NETBIOS queries are also issued in parallel, improving response times for all queries.
LLMNR and NETBIOS are issued in parallel and optimized for IPv4 and IPv6 queries.
Binding order optimization
Interfaces are divided into networks to send parallel DNS queries and prefer binding order responses.
If a specific interface is hijacking DNS names, then for flat names on those networks LLMNR and NETBIOS queries are sent in parallel with DNS queries and the LLMNR or NETBIOS response is preferred.
Asynchronous DNS cache
All the queries in DNS cache service are asynchronous and response timing is optimized.