DNS madness

R

riddle

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For a couple of days now DNS has been failing on my home network and I'm at wit's end.

The setup: 12" PowerBook G4 running 10.4.3. My home connection is RoadRunner cable with a Linksys WRT54G wireless router.

If I take my computer to work or connect to a neighbor's wireless, the problem goes away. It only happens on my own LAN. Numerous reboots haven't helped.

The problem occurs whenever I'm connected to this router, whether wirelessly or wirefully. IP connectivity is fine: if I use a numeric IP address I can ping anything I want. DNS on the router itself is fine: if I connect to the router and use its own diagnostics to ping a hostname, it successfully resolves to an IP address.

I've got three static DNS server addresses configured on the router. All three are working servers: I can use nslookup on my Mac to peform DNS queries against any of them. I've tried explicitly copying those DNS servers to the network preferences on my Mac, for either or both the Airport or built-in ethernet; the problem persists whether or not I configure my Mac to use specific servers.

So what could make DNS fail when connected to a certain router even though DNS is working correctly on the router itself?
 
Someone asked for more detail, so here goes.

The failure is immediate and consists of "www.foo.com could not be found" messages in the browser or "cannot resolve www.foo.com: Unknown host" messages in command-line apps like ping(1).

Here's the output from lookupd -configuration:

ConfigSource: default
LookupOrder: Cache NI DS
MaxIdleServers: 4
MaxIdleThreads: 2
MaxThreads: 64
TimeToLive: 43200
Timeout: 30
ValidateCache: YES
ValidationLatency: 15
_config_name: Global Configuration

LookupOrder: Cache FF DNS NI DS
_config_name: Host Configuration

LookupOrder: Cache FF NI DS
_config_name: Service Configuration

LookupOrder: Cache FF NI DS
_config_name: Protocol Configuration

LookupOrder: Cache FF NI DS
_config_name: Rpc Configuration

TimeToLive: 60
ValidateCache: NO
_config_name: Group Configuration

TimeToLive: 300
ValidateCache: NO
_config_name: Initgroup Configuration

LookupOrder: Cache FF DNS NI DS
_config_name: Network Configuration
 
I bet it is the router. Try connecting directly to your RoadRunner modem to test this theory.
 
I still don't know why this happened, but restoring the Linksys to its factory settings and reconfiguring it from scratch got me back on the air.
 
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