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Groups > comp.os.linux.networking > #3886
| From | Moe Trin <ibuprofin@painkiller.example.tld.invalid> |
|---|---|
| Newsgroups | comp.os.linux.networking |
| Subject | Re: What should I change my DNS to? (combined response) |
| Date | 2016-09-09 20:55 +0000 |
| Organization | Go wash your mouth! |
| Message-ID | <slrnnt68e9.4vr.ibuprofin@planck.phx.az.us> (permalink) |
| References | (4 earlier) <nqlslb$2ct$1@gioia.aioe.org> <slrnnsudm2.aik.ibuprofin@planck.phx.az.us> <nqql5c$1h76$1@gioia.aioe.org> <slrnnt3f9m.sv0.ibuprofin@planck.phx.az.us> <meh9ad-arv.ln1@minas-tirith.valinor> |
On Fri, 9 Sep 2016, in the Usenet newsgroup comp.os.linux.networking, in article
<meh9ad-arv.ln1@minas-tirith.valinor>, Carlos E. R. wrote:
>Moe Trin wrote:
>> A problem is finding a host out on the Internet that will respond
>> (ping has been abused so much that many Internet hosts disable the
>> responder). Lessee, www.ibiblio.org is a host in the Eastern USA,
>> and it has an IP address of 152.19.134.40. I choose it because from
>> experience I know it will _usually_ respond to pings.
>I use google.com. They can afford many pings, they don't care :-)
That's because "google.com" isn't a single host. It's many individual
hosts for load sharing. If you ask a DNS server for the IP address of
google.com, you'll get an answer with short TTL, and the answer will
vary from DNS server to DNS server and (often) from response to
response. I asked a dozen different DNS servers that respond to
non-customer queries using "host -a google.com $IP.ADDR.OF.DNS", and the
answers were:
[ingenio ~]$ grep -w A google.com.IPs
google.com. 285 IN A 216.58.199.14
google.com. 283 IN A 216.58.199.14
google.com. 258 IN A 216.58.203.14
google.com. 158 IN A 216.58.199.110
google.com. 276 IN A 216.58.199.14
google.com. 251 IN A 216.58.203.14
google.com. 299 IN A 216.58.218.174
google.com. 299 IN A 216.58.218.174
google.com. 293 IN A 216.58.217.206
google.com. 72 IN A 216.58.217.206
google.com. 21 IN A 216.58.199.110
google.com. 71 IN A 216.58.217.206
[ingenio ~]$
If you prefer IPv6 instead, the DNS servers gave me six different IPv6
addresses (interestingly, 3 in .au and 3 in .us, even though I'm in the
US and using US based nameservers). The reason for the variety of
answers is because that is what the Google authoritative name servers
are telling everyone who asks. If you were running your own recursive
DNS server, or if you asked one of the authoritative name servers (such
as ns1.google.com.) directly, you probably will get a different answer -
I just did, and got
google.com. 300 IN A 216.58.194.78
The A and AAAA record TTLs are 300 (seconds), and even the MX (mail
exchange) servers are only 600 (seconds). This "low" TTL allows rapid
switching of hostname <-> IP address values. Google (and other
high-bandwidth providers such as Akamai) try to give you the IP of the
"fastest" (closest by hop-count, or least loaded) server at any given
moment. As you are in Europe, you will likely see a different range of
addresses from what I see in the US or the O/P sees in Southeast Asia.
Thus, you may attempt to ping an IP (such as 216.58.199.14) and get no
response - because that particular host is on coffee break at the moment
and the hostname 'google.com' doesn't (AT THIS MOMENT) resolve to that
IP because of that fact. What can I say? ;-)
Old guy
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What should I change my DNS to? F Volker <here@home.net> - 2016-09-06 06:32 +0700
Re: What should I change my DNS to? Moe Trin <ibuprofin@painkiller.example.tld.invalid> - 2016-09-06 03:35 +0000
Re: What should I change my DNS to? F Volker <here@home.net> - 2016-09-06 13:48 +0700
Re: What should I change my DNS to? William Unruh <unruh@invalid.ca> - 2016-09-06 07:25 +0000
Re: What should I change my DNS to? F Volker <here@home.net> - 2016-09-06 14:53 +0700
Re: What should I change my DNS to? Dan Purgert <dan@djph.net> - 2016-09-06 09:40 +0000
Re: What should I change my DNS to? William Unruh <unruh@invalid.ca> - 2016-09-06 10:35 +0000
Re: What should I change my DNS to? Dan Purgert <dan@djph.net> - 2016-09-06 11:09 +0000
Re: What should I change my DNS to? F Volker <here@home.net> - 2016-09-07 08:53 +0700
Re: What should I change my DNS to? William Unruh <unruh@invalid.ca> - 2016-09-07 08:24 +0000
Re: What should I change my DNS to? "Carlos E. R." <robin_listas@invalid.es> - 2016-09-07 14:02 +0200
Re: What should I change my DNS to? F Volker <here@home.net> - 2016-09-08 06:42 +0700
Re: What should I change my DNS to? "Carlos E. R." <robin_listas@invalid.es> - 2016-09-08 03:10 +0200
Re: What should I change my DNS to? F Volker <here@home.net> - 2016-09-08 09:43 +0700
Re: What should I change my DNS to? (combined response) Moe Trin <ibuprofin@painkiller.example.tld.invalid> - 2016-09-06 21:36 +0000
Re: What should I change my DNS to? (combined response) "Carlos E. R." <robin_listas@invalid.es> - 2016-09-07 00:48 +0200
Re: What should I change my DNS to? (combined response) William Unruh <unruh@invalid.ca> - 2016-09-07 08:18 +0000
Re: What should I change my DNS to? (combined response) "Carlos E. R." <robin_listas@invalid.es> - 2016-09-07 14:08 +0200
Re: What should I change my DNS to? (combined response) Moe Trin <ibuprofin@painkiller.example.tld.invalid> - 2016-09-07 21:52 +0000
Re: What should I change my DNS to? (combined response) "Carlos E. R." <robin_listas@invalid.es> - 2016-09-08 00:52 +0200
Re: What should I change my DNS to? (combined response) F Volker <here@home.net> - 2016-09-07 09:13 +0700
Re: What should I change my DNS to? (combined response) "Carlos E. R." <robin_listas@invalid.es> - 2016-09-07 04:26 +0200
Re: What should I change my DNS to? (combined response) F Volker <here@home.net> - 2016-09-07 09:41 +0700
Re: What should I change my DNS to? (combined response) "Carlos E. R." <robin_listas@invalid.es> - 2016-09-07 14:11 +0200
Re: What should I change my DNS to? (combined response) F Volker <here@home.net> - 2016-09-07 10:59 +0700
Re: What should I change my DNS to? (combined response) Moe Trin <ibuprofin@painkiller.example.tld.invalid> - 2016-09-07 06:53 +0000
Re: What should I change my DNS to? (combined response) Dan Purgert <dan@djph.net> - 2016-09-07 11:02 +0000
Re: What should I change my DNS to? (combined response) "Carlos E. R." <robin_listas@invalid.es> - 2016-09-07 14:21 +0200
Re: What should I change my DNS to? (combined response) Dan Purgert <dan@djph.net> - 2016-09-07 14:09 +0000
Re: What should I change my DNS to? (combined response) "Carlos E. R." <robin_listas@invalid.es> - 2016-09-07 21:53 +0200
Re: What should I change my DNS to? (combined response) Dan Purgert <dan@djph.net> - 2016-09-08 11:06 +0000
Re: What should I change my DNS to? (combined response) "Carlos E. R." <robin_listas@invalid.es> - 2016-09-08 15:22 +0200
Re: What should I change my DNS to? (combined response) Moe Trin <ibuprofin@painkiller.example.tld.invalid> - 2016-09-07 06:55 +0000
Re: What should I change my DNS to? (combined response) F Volker <here@home.net> - 2016-09-07 14:27 +0700
Re: What should I change my DNS to? (combined response) "Carlos E. R." <robin_listas@invalid.es> - 2016-09-07 14:28 +0200
Re: What should I change my DNS to? (combined response) Stefan Monnier <monnier@iro.umontreal.ca> - 2016-09-07 09:32 -0400
Re: What should I change my DNS to? (combined response) Moe Trin <ibuprofin@painkiller.example.tld.invalid> - 2016-09-07 21:50 +0000
Re: What should I change my DNS to? (combined response) William Unruh <unruh@invalid.ca> - 2016-09-07 08:29 +0000
Re: What should I change my DNS to? (combined response) F Volker <here@home.net> - 2016-09-08 10:15 +0700
Re: What should I change my DNS to? (combined response) Moe Trin <ibuprofin@painkiller.example.tld.invalid> - 2016-09-08 19:34 +0000
Re: What should I change my DNS to? (combined response) "Carlos E. R." <robin_listas@invalid.es> - 2016-09-09 03:56 +0200
Re: What should I change my DNS to? (combined response) Moe Trin <ibuprofin@painkiller.example.tld.invalid> - 2016-09-09 20:55 +0000
Re: What should I change my DNS to? (combined response) "Carlos E. R." <robin_listas@invalid.es> - 2016-09-10 02:47 +0200
Re: What should I change my DNS to? (combined response) Bit Twister <BitTwister@mouse-potato.com> - 2016-09-10 08:27 +0000
Re: What should I change my DNS to? (combined response) Moe Trin <ibuprofin@painkiller.example.tld.invalid> - 2016-09-10 22:53 +0000
Re: What should I change my DNS to? "Carlos E. R." <robin_listas@invalid.es> - 2016-09-06 13:35 +0200
Re: What should I change my DNS to? Aragorn <thorongil@telenet.be.invalid> - 2016-09-06 14:06 +0200
Re: What should I change my DNS to? "Carlos E. R." <robin_listas@invalid.es> - 2016-09-06 14:27 +0200
Re: What should I change my DNS to? Dan Purgert <dan@djph.net> - 2016-09-06 13:03 +0000
Re: What should I change my DNS to? "Carlos E. R." <robin_listas@invalid.es> - 2016-09-06 17:01 +0200
Re: What should I change my DNS to? Dan Purgert <dan@djph.net> - 2016-09-06 16:25 +0000
Re: What should I change my DNS to? Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2016-09-06 21:37 +0300
Re: What should I change my DNS to? "Carlos E. R." <robin_listas@invalid.es> - 2016-09-06 23:42 +0200
Re: What should I change my DNS to? F Volker <here@home.net> - 2016-09-07 09:26 +0700
Re: What should I change my DNS to? Roger Blake <rogblake@iname.invalid> - 2016-09-06 12:54 +0000
Re: What should I change my DNS to? F Volker <here@home.net> - 2016-09-07 09:28 +0700
Re: What should I change my DNS to? William Unruh <unruh@invalid.ca> - 2016-09-07 08:25 +0000
Re: What should I change my DNS to? Moe Trin <ibuprofin@painkiller.example.tld.invalid> - 2016-09-07 03:29 +0000
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