Discussion in 'Tomato Firmware' started by jestermiami, Jul 12, 2008.
dnsmasq maintains a cache of DNS addresses it has resolved. Any cache improves lookup performance.
But the client computer OS already has such a DNS cache anyway. I doubt that for a small home network there's a real benefit to caching DNS at the router level. The benefit of another client computer on the LAN to not having to go out for a DNS resolution is negligible in my opinion.
Well, caches are everywhere; even your browser maintains a DNS cache both for performance and security purposes. Disabling any one of them may or may not be a performance problem. If you believe it's negligible, I'm not going to argue with you.
If you frequently visit the same site, having the DNS cache on your router will be an order of magnitude or two faster than grabbing it from OpenDNS servers. Your router will most likely have a delay of about 1 ms, while OpenDNS will likely be at least 20 ms. Granted that's not much of a difference overall and you'd be hard pressed to actualy see a difference in speed.
Except that the OS already has its own cache which is way faster than even going to the router ...
Another benefit is resolution of local names. Lets you have one central place on your LAN to assign names to addresses, especially if you have a mixed network (not just Windows).
I'm not sure if the router dnsmasq cache has any real speed benefit. But it allows me to run xcooling's ad blocking script which as I understand it works by dnsmasq cache poisoning, ;-)
A few weeks ago my ISP had problem with its DNS servers. MAny poeple complaining they could not suf on the web. I had no problem. Didn't notice there was one.I think the DNS cache in the router and Tomato solved the problem for me.
That can't be, the cache is only temporary, each DNS record has a TTL (time-to-live), usually small. If properly implemented, the cache should respect the TTL. The cache in the router shouldn't be much different than the OS cache.
Ah, good point. This is useful indeed. For my LAN, I prefer to maintain a hosts file that I synchronize on all computers.
Here in Windows XP the DNS client service is deactivated. I don't know if the OS maintains a cache in this case.