Even we technically minded folk sometimes come across problems that are so inconceivably annoying and stealthy that they're almost impossible to track down without a great deal of patience. Here's one such problem that I felt needed to be shared because many people around the Internet have been hit by it.
Essentially this is a problem that afflicts Windows Vista and 7 but appears to spare Windows XP due to the absence of automated network management. One day you can be using your PC quite happily and then the next you'll boot it to find that the Internet connectivity no longer works, at least until you reboot the PC a 2nd time or disable and re-enable the Network Adapter.
Under Vista that would pop into the event viewer as being a problem/conflict of some sort with your routers DHCP server, sometimes causing the PC to hang upon load. With Windows 7 it appears more inclined to stop the internet working altogether because 7 tries to fix the problem behind the scenes but only makes it worse.
Now I've seen this issue sporadically across many different computers since the Vista days but it's always been hard to track down. In the end it has turned out to be caused by Apple's Bonour "service":
Ah ha! Now the thing about Bonjour is that lots of software ships with it and the mDNSResponder service quietly slips into your computer without ever you knowing. By the description it ends up looking like a service that you wouldn't want to disable and is thus often overlooked.
In my case I found that it came with Adobe Photoshop (CS3), but iTunes and Apple's usual software ilk also include it. The problem is that this is older than Windows 7 and while it caused problems with Vista too, with Windows 7 it can really screw the OS's own DHCP assignments for your router. I believe the latest Bonjour service might be fine, I haven't tried, but older versions definitely cause problems for 7.
In the end I solved this by ruthlessly hunting down the mDNSResponder.exe process/file and renaming it. Now the Internet works again and the event viewer isn't often moaning about undefined DHCP conflicts, so that's one hugely annoying and sporadic 3 year problem fixed lol.
Essentially this is a problem that afflicts Windows Vista and 7 but appears to spare Windows XP due to the absence of automated network management. One day you can be using your PC quite happily and then the next you'll boot it to find that the Internet connectivity no longer works, at least until you reboot the PC a 2nd time or disable and re-enable the Network Adapter.
Under Vista that would pop into the event viewer as being a problem/conflict of some sort with your routers DHCP server, sometimes causing the PC to hang upon load. With Windows 7 it appears more inclined to stop the internet working altogether because 7 tries to fix the problem behind the scenes but only makes it worse.
Now I've seen this issue sporadically across many different computers since the Vista days but it's always been hard to track down. In the end it has turned out to be caused by Apple's Bonour "service":
1. What is Bonjour?
Bonjour, also known as zero-configuration networking, enables automatic discovery of computers, devices, and services on IP networks. Bonjour uses industry standard IP protocols to allow devices to automatically discover each other without the need to enter IP addresses or configure DNS servers. Specifically, Bonjour enables automatic IP address assignment without a DHCP server, name to address translation without a DNS server, and service discovery without a directory server. Bonjour is an open protocol which Apple has submitted to the IETF as part of the ongoing standards-creation process. To learn more, check out the Bonjour Protocol Specifications which detail the technologies that make up Link-Local and Wide-Area Bonjour.
2. What is mDNSResponder?
mDNSResponder is a Bonjour system service that implements Multicast DNS Service Discovery for discovery of services on the local network, and Unicast DNS Service Discovery for discovery of services anywhere in the world. mDNSResponder is built into Mac OS X and can be downloaded as part of Bonjour for Windows. Applications like iTunes, iPhoto, iChat and Safari use mDNSResponder to implement zero-configuration network music sharing, photo sharing, chatting and file sharing, and discovery of remote user interfaces for hardware devices like printers and web cameras. mDNSResponder is also used to discover and print to Bonjour printers and USB printers connected to the AirPort Extreme and Express base stations. mDNSResponder is open source, and hardware device manufacturers are encouraged to embed the mDNSResponder source code directly into their products to benefit from zero-configuration networking.
Ah ha! Now the thing about Bonjour is that lots of software ships with it and the mDNSResponder service quietly slips into your computer without ever you knowing. By the description it ends up looking like a service that you wouldn't want to disable and is thus often overlooked.
In my case I found that it came with Adobe Photoshop (CS3), but iTunes and Apple's usual software ilk also include it. The problem is that this is older than Windows 7 and while it caused problems with Vista too, with Windows 7 it can really screw the OS's own DHCP assignments for your router. I believe the latest Bonjour service might be fine, I haven't tried, but older versions definitely cause problems for 7.
In the end I solved this by ruthlessly hunting down the mDNSResponder.exe process/file and renaming it. Now the Internet works again and the event viewer isn't often moaning about undefined DHCP conflicts, so that's one hugely annoying and sporadic 3 year problem fixed lol.























