what does "max-ncache-ttl 0;" mean?

[blrmaani]

man pages for named.conf says "max-ncache-ttl <integer>" and only talks about default values and max values - no mention of minimum-value.

Does "max-ncache-ttl 0;" mean never cache negative queries (queries resulting in NXDOMAIN) or does it mean cache negative queries forever?

Too lazy to test this option or look bind code :), hence posting here - apologies in advance..!!

Blr

[John W. Blue]

http://www.google.com/search?q=max-ncache-ttl+0

John

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[A. Renald Niswady]

max-ncache-ttl sets the maximum time (in seconds) for which the server will cache negative (NXDOMAIN) answers (positives are defined by max-cache-ttl). The default max-ncache-ttl is 10800 seconds (3 hours). max-ncache-ttl cannot exceed 7 days and will be silently truncated to 7 days if set to a greater value. This statement may be used in view or a global options clause.

Regards,
A. Renald Niswady
[NOC-System] Orion Cyber Internet

---

PT Orion Cyber Internet
Gedung Cyber Lt. 1 Jl. Kuningan Barat No. 8, Jakarta Selatan 12710
Telp: 021 5265566 - Fax: 021 6280883
Homepage: http://www.orion.net.id
Internet Access, Webhosting, Colocation, Games and More.

---

From: "blrmaani" <blrm...@gmail.com>
To: comp-protoc...@isc.org
Sent: Wednesday, March 2, 2016 2:13:29 PM

[John W. Blue]

Now quote your source.

 

;)

[A. Renald Niswady]

hehehe,

http://www.zytrax.com/books/dns/ch7/hkpng.html#max-ncache-ttl

i found zytrax site is really helpful

Regards
-Renald-

---

From: "John W. Blue" <john...@rrcic.com>
To: "A. Renald Niswady" <rena...@orion.net.id>, "blrmaani" <blrm...@gmail.com>
Cc: comp-protoc...@isc.org
Sent: Wednesday, March 2, 2016 2:27:49 PM
Subject: RE: what does "max-ncache-ttl 0;" mean?

[blrmaani]

On Tuesday, March 1, 2016 at 11:34:09 PM UTC-8, A. Renald Niswady wrote:
> hehehe,
>
>
> http://www.zytrax.com/books/dns/ch7/hkpng.html#max-ncache-ttl
>
>
> i found zytrax site is really helpful
>
>
>
>
>
>
> Regards
> -Renald-
>

> From: "John W. Blue" <john...@rrcic.com>
> To: "A. Renald Niswady" <rena...@orion.net.id>, "blrmaani" <blrm...@gmail.com>
> Cc: comp-protoc...@isc.org
> Sent: Wednesday, March 2, 2016 2:27:49 PM
> Subject: RE: what does "max-ncache-ttl 0;" mean?
>
>
>
>
>
>
>
>
>
>
>
>
> Now quote your source.
>
>  
>
> ;)
>
>  
>
>
>
>
>
> From: bind-user...@lists.isc.org [mailto:bind-user...@lists.isc.org]
> On Behalf Of A. Renald Niswady
>
> Sent: Wednesday, March 02, 2016 1:23 AM
>
> To: blrmaani
>
> Cc: comp-protoc...@isc.org
>
> Subject: Re: what does "max-ncache-ttl 0;" mean?
>
>
>
>  
>
>
>
>
>
> max-ncache-ttl sets the maximum time (in seconds) for which the server will cache negative (NXDOMAIN) answers
> (positives are defined by
> max-cache-ttl). The default max-ncache-ttl is 10800 seconds (3 hours). max-ncache-ttl cannot exceed 7 days and will be silently truncated to 7 days if set to a greater value. This statement may be used in
> view or a global
> options clause.
>
>
>
>
>  
>
>
>
>
>
>
> Regards,
>
> A. Renald Niswady
>
> [NOC-System] Orion Cyber Internet
>
>
>
>
>
>
>
>

> PT Orion Cyber Internet
>
> Gedung Cyber Lt. 1 Jl. Kuningan Barat No. 8, Jakarta Selatan 12710
>
> Telp: 021 5265566 - Fax: 021 6280883
>
> Homepage:
>
> http://www.orion.net.id
>
> Internet Access, Webhosting, Colocation, Games and More.
>
>
>  
>
>
>
>
>
>
>
>

> From:
> "blrmaani" <blrm...@gmail.com>
>
> To: comp-protoc...@isc.org
>
> Sent: Wednesday, March 2, 2016 2:13:29 PM
>
> Subject: what does "max-ncache-ttl 0;" mean?
>
>
>
>  
>
>
> man pages for named.conf says "max-ncache-ttl <integer>" and only talks about default values and max values - no mention of minimum-value.
>
>
>
>
>  
>
>
> Does "max-ncache-ttl 0;" mean never cache negative queries (queries resulting in NXDOMAIN) or does it mean cache negative queries forever?
>
>
>
>  
>
>
> Too lazy to test this option or look bind code :), hence posting here - apologies in advance..!!
>
>
>
>  
>
>
> Blr
>
> _______________________________________________
>
> Please visit https://lists.isc.org/mailman/listinfo/bind-users to unsubscribe from this list
>
>
>
>  
>
>
> bind-users mailing list
>
> bind-...@lists.isc.org
>
> https://lists.isc.org/mailman/listinfo/bind-users
>
>
>
>
>
>  

No definite answer anywhere when value is set to 0

[MURTARI, JOHN]

Folks,

 

                Never has so little been said by so many?  The OP asked:

======

man pages for named.conf says "max-ncache-ttl <integer>" and only talks about default values and max values - no mention of minimum-value.

Does "max-ncache-ttl 0;" mean never cache negative queries (queries resulting in NXDOMAIN) or does it mean cache negative queries forever?

Too lazy to test this option or look bind code :), hence posting here - apologies in advance..!!

======

 

                So far, all the postings I’ve seen just echo what he already said (and knows).  The question is – what happens when you set it to ZERO?

 

                I’m wondering myself – anyone have a real answer?

                Smiles!

John

 

----------------   
John Murtari – jm5...@att.com

Ciberspring

office: 315-944-0998

cell: 315-430-2702

 

[Tony Finch]

MURTARI, JOHN <jm5...@att.com> wrote:
>
> So far, all the postings I've seen just echo what he already said (and

> knows). The question is - what happens when you set it to ZERO?
>
> I'm wondering myself - anyone have a real answer?

The code says zero means zero, so in effect it would disable negative
cacheing.

Tony.
--
f.anthony.n.finch <d...@dotat.at> http://dotat.at/
Thames, Dover, Wight: West veering northwest 7 to severe gale 9, decreasing 4
or 5 later. Rough or very rough, becoming moderate or rough later. Squally
showers. Good, occasionally poor.

[Matus UHLAR - fantomas]

>MURTARI, JOHN <jm5...@att.com> wrote:
>> So far, all the postings I've seen just echo what he already said (and
>> knows). The question is - what happens when you set it to ZERO?
>>
>> I'm wondering myself - anyone have a real answer?

On 02.03.16 13:29, Tony Finch wrote:
>The code says zero means zero, so in effect it would disable negative
>cacheing.

which means, DON'T DO THAT. anyone searching for nonexisting DNS names (e.g.
because of a misconfiguration) could easily DoS your server.
--
Matus UHLAR - fantomas, uh...@fantomas.sk ; http://www.fantomas.sk/
Warning: I wish NOT to receive e-mail advertising to this address.
Varovanie: na tuto adresu chcem NEDOSTAVAT akukolvek reklamnu postu.
"To Boot or not to Boot, that's the question." [WD1270 Caviar]

[Darcy Kevin (FCA)]

I wouldn't be so quick to assume that.

Nota bene this part of the ARM:

"Integers may take values 0 <= value <= 18446744073709551615, though certain parameters (such as max-journal-size) may use a more limited range within these extremes. In most cases, setting a value to 0 does not literally mean zero; it means 'undefined"' or 'as big as possible', depending on the context. See the explanations of particular parameters that use size_spec for details on how they interpret its use."

So, it might actually mean "as big as possible".

Consult the source code to be sure.
- Kevin


----------------------------------------------------------------------
Kevin Darcy
NAFTA Information Security Projects

FCA US LLC
1075 W Entrance Dr,
Auburn Hills, MI 48326
USA

Telephone: +1 (248) 838-6601
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Email: kevin...@fcagroup.com

-----Original Message-----
From: bind-user...@lists.isc.org [mailto:bind-user...@lists.isc.org] On Behalf Of Tony Finch
Sent: Wednesday, March 02, 2016 8:29 AM
To: MURTARI, JOHN
Cc: bind-...@lists.isc.org
Subject: Re: what does "max-ncache-ttl 0;" mean?

MURTARI, JOHN <jm5...@att.com> wrote:
>
> So far, all the postings I've seen just echo what he already said (and
> knows). The question is - what happens when you set it to ZERO?
>
> I'm wondering myself - anyone have a real answer?

The code says zero means zero, so in effect it would disable negative cacheing.

Tony.
--
f.anthony.n.finch <d...@dotat.at> http://dotat.at/ Thames, Dover, Wight: West veering northwest 7 to severe gale 9, decreasing 4 or 5 later. Rough or very rough, becoming moderate or rough later. Squally showers. Good, occasionally poor.

[Evan Hunt]

> So, it might actually mean "as big as possible".
>
> Consult the source code to be sure.

Tony did consult the source code, upthread. And he was correct: for this
particular option, zero does mean zero.

--
Evan Hunt -- ea...@isc.org
Internet Systems Consortium, Inc.