Multihomed Windows 10 DNS resolution timeouts
Microsoft has in Windows 10 substantially modified or rewritten the DNS Resolver.
The biggest change was to issue DNS queries to all adapters in parallel, then take the first answer to arrive. Unfortunately the new code contains bugs and omissions, and it seems that rather than take the first answer, it waits for all answers. If one of the DNS queries will time-out, this means a 10-seconds wait before the DNS is resolved.
This bug will undoubtedly be fixed in a future update of Windows 10. Until then, to return the behavior as much as possible to that of previous Windows versions, the following registry modifications exist :
DisableSmartNameResolution (DWORD)
In registry key
HKEY_LOCAL_MACHINE\Software\Policies\Microsoft\Windows NT\DNSClient.
The value is 1 to disable, 0 to enable smart resolution.
From Turn off smart multi-homed name resolution :
Specifies that a multi-homed DNS client should optimize name resolution across networks. The setting improves performance by issuing parallel DNS link local multicast name resolution (LLMNR) and NetBIOS over TCP/IP (NetBT) queries across all networks. In the event that multiple positive responses are received the network binding order is used to determine which response to accept.If you enable this policy setting the DNS client will not perform any optimizations. DNS queries will be issued across all networks first. LLMNR queries will be issued if the DNS queries fail followed by NetBT queries if LLMNR queries fail.If you disable this policy setting or if you do not configure this policy setting name resolution will be optimized when issuing DNS LLMNR and NetBT queries.
DisableParallelAandAAAA (DWORD)
In registry key
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Dnscache\Parameters.
The value is 0 to enable, 1 to disable
DNS A and AAAA queries from executing in parallel on all configured DNS servers,
with the fastest response being theoretically accepted first.
source
SMHNR is slightly changed for Windows 10 compared to Windows 8. In Windows 10, you can’t turn it off via the registry.
For Windows 10, you can use "Local Policies" to deactivate the feature. Follow the steps below to do this:
- Press WIN+R and write gpedit.msc
- Expand Administrative templates Expand Network
- Click DNS-client Double-click "Turn off smart multi-homed name resolution"
- Check the box called "Enabled"
- Click "Apply all" and then "OK"