Re: Speeding up DNS change propagation

2015-09-18 Thread Alan Clegg
Remember, however, that if you are clearing YOUR caches by restarting, everyone else around the world is still seeing the data with the original TTL still "in place". The right thing to do is to lower the TTL on the auth servers to an acceptable "outage" value before you make the change, wait for

Re: Speeding up DNS change propagation

2015-09-18 Thread Bob Harold
On Fri, Sep 18, 2015 at 2:35 PM, Danny Sinang wrote: > Hi, > > Our vendor is changing their FTP server's IP address tomorrow. > > 1. How can I tell how long their DNS change will propagate to us ? > > a. Do I just run dig a "ftp.example.com" and look for the TTL for > that DNS entry ? >

Re: Speeding up DNS change propagation

2015-09-18 Thread Danny Sinang
Ah, many thanks ! :) On Fri, Sep 18, 2015 at 3:37 PM, John Miller wrote: > The .com nameservers don't know anything about ftp.example.com; they > just know the nameservers for example.com. So have no fear -- BIND > will not cache an upstream response for ftp.example.com: you'll only > hear abou

Re: Speeding up DNS change propagation

2015-09-18 Thread John Miller
The .com nameservers don't know anything about ftp.example.com; they just know the nameservers for example.com. So have no fear -- BIND will not cache an upstream response for ftp.example.com: you'll only hear about ftp.example.com from the example.com nameservers. Pretty much all upstream namese

Re: Speeding up DNS change propagation

2015-09-18 Thread Danny Sinang
As a follow-up to your answer for question #2, after my clearing the cache or restarting BIND, won't BIND find an old cache of "ftp.example.com" in the ".com" top level DNS server ? Regards, Danny On Fri, Sep 18, 2015 at 2:51 PM, John Miller wrote: > On Fri, Sep 18, 2015 at 2:35 PM, Danny Sinan

Re: Speeding up DNS change propagation

2015-09-18 Thread John Miller
On Fri, Sep 18, 2015 at 2:35 PM, Danny Sinang wrote: > Hi, > > Our vendor is changing their FTP server's IP address tomorrow. > > 1. How can I tell how long their DNS change will propagate to us ? Whatever TTL you have cached when the vendor makes the switch is how long it'll take for your cachin

Speeding up DNS change propagation

2015-09-18 Thread Danny Sinang
Hi, Our vendor is changing their FTP server's IP address tomorrow. 1. How can I tell how long their DNS change will propagate to us ? a. Do I just run dig a "ftp.example.com" and look for the TTL for that DNS entry ? b. Every time I run that command, the TTL is shrinking. How do I find