[Dnsmasq-discuss] Long nslookup times
Donald Muller
donmuller22 at outlook.com
Fri Mar 2 06:14:33 GMT 2018
> -----Original Message-----
> From: Dnsmasq-discuss [mailto:dnsmasq-discuss-
> bounces at lists.thekelleys.org.uk] On Behalf Of Geert Stappers
> Sent: Wednesday, February 21, 2018 1:18 PM
> To: dnsmasq-discuss at lists.thekelleys.org.uk
> Subject: Re: [Dnsmasq-discuss] Long nslookup times
>
> On Wed, Feb 21, 2018 at 07:02:45PM +0100, Geert Stappers wrote:
> > On Wed, Feb 21, 2018 at 05:03:34PM +0000, Donald Muller wrote:
> > > > > > On Wed, Jan 31, 2018 at 10:22:53AM +0100, Geert Stappers wrote:
> > > > > > > On Tue, Jan 30, 2018 at 05:08:05PM +0000, Donald Muller wrote:
> > > > > > > >
> > > > > > > > Using Microsoft DNS server [~] # time nslookup
> > > > > > > > www.microsoft.com 192.168.22.200 Address 1:
> > > > > > > > 192.168.22.200 djmfs1.djmuller.com
> > > > > > >
> > > > > > > Programm nslookup did a reverse lookup on used DNS address
> > > > > > > and got back a FQDN
> > > > > > >
> > > > > > > > Using dnsmasq
> > > > > > > > [~] # time nslookup www.microsoft.com 192.168.22.220 Address
> 1:
> > > > > > > > 192.168.22.220 DJMFS2
> > > > > > >
> > > > > > > Non Fully Qualified Domain Name for the used DNS address
>
> So we know that the reverse DNS data source is some what sloppy
> configured.
>
> ||| 192.168.22.200 djmfs1.djmuller.com
> ||| 192.168.22.220 DJMFS2
>
> But the real thing I'm trying to tell: extra (unwanted??) reverse lookup
> happen
>
>
> > > > > > > Wow, a full forty seconds ...
> > > > > > >
> > > >
> > > > I'm not convinced that the culprit is in dnsmasq.
> > > > Please continue to find proof ...
>
> Because you have a interesting probleem ...
>
>
> > > > > > > > What additional information do you need?
> > > > > All devices, including the router, are connected at 1GB to a switch.
> > > >
> > > > The testclient what does it have in /etc/resolv.conf while testing?
> > > > Other tools for `nslookup`, such as `dig` and `host`, what timing
> > > > results have those?
> > > > The QNAP NAS with dnsmasq, how much traffic must it handle?
> > >
> > > The test client has the following in reslov.conf
> > >
> > > [~] # cat /etc/resolv.conf
> > > nameserver 192.168.22.220
> > > nameserver 192.168.22.242
> > >
> > > host shows the following:
> > >
> > > [~] # time host www.microsoft.com 192.168.22.220 Using domain
> > > server:
> > > Name: 192.168.22.220
> > > Address: 192.168.22.220#53
> > > Aliases:
> > >
> > > www.microsoft.com is an alias for www.microsoft.com-c-3.edgekey.net.
> > > www.microsoft.com-c-3.edgekey.net is an alias for www.microsoft.com-
> c-3.edgekey.net.globalredir.akadns.net.
> > > www.microsoft.com-c-3.edgekey.net.globalredir.akadns.net is an alias
> for e13678.dspb.akamaiedge.net.
> > > e13678.dspb.akamaiedge.net has address 104.88.47.193
> > > e13678.dspb.akamaiedge.net has IPv6 address 2001:418:143c:19e::356e
> > > e13678.dspb.akamaiedge.net has IPv6 address 2001:418:143c:1a9::356e
> > >
> > > real 0m0.050s
> > > user 0m0.001s
> > > sys 0m0.001s
>
> That is much better than forty seconds ...
>
> > > dig is not installed.
>
> Install it. Rule out that we are dealing with a bogus nslookup.
Results of dig
[~] # dig www.microsoft.com 192.168.22.220
; <<>> DiG 9.11.2 <<>> www.microsoft.com 192.168.22.220
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 54000
;; flags: qr rd ra; QUERY: 1, ANSWER: 4, AUTHORITY: 0, ADDITIONAL: 1
;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 1280
;; QUESTION SECTION:
;www.microsoft.com. IN A
;; ANSWER SECTION:
www.microsoft.com. 2025 IN CNAME www.microsoft.com-c-3.edgekey.net.
www.microsoft.com-c-3.edgekey.net. 13945 IN CNAME www.microsoft.com-c-3.edgekey.net.globalredir.akadns.net.
www.microsoft.com-c-3.edgekey.net.globalredir.akadns.net. 72 IN CNAME e13678.dspb.akamaiedge.net.
e13678.dspb.akamaiedge.net. 19 IN A 23.206.169.201
;; Query time: 10 msec
;; SERVER: 192.168.22.220#53(192.168.22.220)
;; WHEN: Fri Mar 02 01:13:06 EST 2018
;; MSG SIZE rcvd: 213
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 22575
;; flags: qr aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1
;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;192.168.22.220. IN A
;; ANSWER SECTION:
192.168.22.220. 0 IN A 192.168.22.220
;; Query time: 0 msec
;; SERVER: 192.168.22.220#53(192.168.22.220)
;; WHEN: Fri Mar 02 01:13:06 EST 2018
;; MSG SIZE rcvd: 59
[~] #
>
> > >
> > > The QNAP NAS is not handling much traffic. If is a home file server with
> minimal traffic.
> > >
> > > I also set up dnsmasq on a second NAS with just DNS running, no
> > > DHCP. This NAS is used for backups so normally has no traffic. I get
> > > the same long times
> > >
> > > [~] # time nslookup www.microsoft.com 192.168.22.242
> > > Server: 192.168.22.242
> > > Address 1: 192.168.22.242 djmfs3.djmuller.com
>
> A reverse DNS lookup was performed
> > >
> > > Name: www.microsoft.com
> > > Address 1: 104.88.47.193
> > > a104-88-47-193.deploy.static.akamaitechnologies.com
>
> A reverse DNS lookup was performed
>
> > > Address 2: 2001:418:143c:19e::356e
> > > Address 3: 2001:418:143c:1a9::356e
> > >
> > > real 0m40.071s
> > > user 0m0.000s
> > > sys 0m0.001s
> > >
> > > What times do you get if you do a nslookup on www.microsoft.com?
> >
> > | $ time nslookup www.microsoft.com 172.24.0.7
> > | Server: 172.24.0.7
> > | Address: 172.24.0.7#53
>
> No sign that nslookup did a reverse lookup.
>
> > | Non-authoritative answer:
> > | www.microsoft.com canonical name = www.microsoft.com-c-
> 3.edgekey.net.
> > | www.microsoft.com-c-3.edgekey.net canonical name =
> www.microsoft.com-c-3.edgekey.net.globalredir.akadns.net.
> > | www.microsoft.com-c-3.edgekey.net.globalredir.akadns.net
> canonical name = e13678.dspb.akamaiedge.net.
> > | Name: e13678.dspb.akamaiedge.net
> > | Address: 104.73.152.80
>
> No sign that nslookup did a reverse lookup.
>
> > | real 0m0,261s
> > | user 0m0,006s
> > | sys 0m0,006s
>
> Considered "fast"
>
> > | $ time host www.microsoft.com 172.24.0.7 Using domain server:
> > | Name: 172.24.0.7
> > | Address: 172.24.0.7#53
> > | Aliases:
> > |
> > | www.microsoft.com is an alias for www.microsoft.com-c-3.edgekey.net.
> > | www.microsoft.com-c-3.edgekey.net is an alias for www.microsoft.com-
> c-3.edgekey.net.globalredir.akadns.net.
> > | www.microsoft.com-c-3.edgekey.net.globalredir.akadns.net is an alias
> for e13678.dspb.akamaiedge.net.
> > | e13678.dspb.akamaiedge.net has address 104.73.152.80
> > | e13678.dspb.akamaiedge.net has IPv6 address 2a02:26f0:f4:196::356e
> > | e13678.dspb.akamaiedge.net has IPv6 address 2a02:26f0:f4:19f::356e
> > |
> > | real 0m0,096s
> > | user 0m0,008s
> > | sys 0m0,004s
>
> faster as nslookup.
>
>
> Groeten
> Geert Stappers
> --
> Leven en laten leven
>
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