[dns-operations] Anycast vs. unicast NS

[Jim Reid]

On 20 Mar 2011, at 20:03, Bill Woodcock wrote:

> On Mar 20, 2011, at 12:21 PM, Jim Reid wrote:
>> Extra complexity in server configuration
>> More complicated systems & network management (procedures)
>> More complicated monitoring arrangements
>> More elaborate network operations and support (procedures)
>
> Aren't all of these differences dependent on the number of servers,  
> rather than whether they're anycast or unicast?

No Bill. I was/am specifically referring to the special sauce that  
goes on inside an anycast node and then to assimilate that node into  
the anycast cloud. I hoped that was clear from my previous posting. Oh  
well...

There are additional failure modes here that aren't found at a unicast  
server, all other things being equal. I'd be very surprised if PCH  
configures and operates its anycast DNS servers compared in *exactly*  
the same way as any unicast ones it operates.

> I think you're just arguing against having multiple servers, not  
> against anycast.

You may think that, but you'd be very wrong to suggest I was making  
that argument because I'm not.

I am saying that an all-anycast solution *is* a SPoF if it's the only  
DNS service offering that's used: ie sourced from one provider, no  
matter how robust and redundant their service is. YMMV.