dscacheutil -flushcache and -killall -INFO mDNSResponder

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dscacheutil -flushcache and -killall -INFO mDNSResponder

I am probably not understanding how the DNS resolver cache operates on a Mac OS X 10.6 operating system.......but here's my issue:

I use dscacheutil -flushcache and killall -INFO mDNSResponder and my system.log still shows PTR and TXT records? Why?

My A records are flushed but 60 entries (ex: PTR and TXT records) still exist. I am used to Windows and the Windows "ipconfig /flushdns" flushes all records. Does the "dscacheutil -flushcache" with the DNS resolver (mDNSResponde) respond differently than a windows system using "ipconfig /flushdns"?

I thought when I typed ""dscacheutil -flushcache", that all records (PTR, TXT and A ) would disappear from the cache.

Thanks, Secretariat

Xserve, Mac OS X (10.6.7)

Posted on Apr 30, 2011 4:26 PM

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Answer 1

Secretariat Author

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Apr 30, 2011 7:45 PM in response to TeenTitan

No, I turned the airport off on the post dated Apr 30, 2011 6:00 PM. Once I turned the airport off, the entries in the cache went from 60 records to 12 records. It looks like the 12 records (listed above) are from the mDNSResponder process that Bonjour uses locally.

Geez, it looks like the cache auto-populates rather quickly after a "dscacheutil -flushcache".

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Answer 2

TeenTitan

Level 4

2,640 points

Apr 30, 2011 4:49 PM in response to Secretariat

are you resetting the cache while connect to a network? have you tried resetting the cache with no network connections?

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Answer 3

Secretariat Author

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Apr 30, 2011 4:42 PM in response to TeenTitan

Here is what I see:

Apr 30 16:40:25 SVWS106PM1 mDNSResponder[18]: SIGHUP: Purge cache

Apr 30 16:40:45 SVWS106PM1 mDNSResponder[18]: ---- BEGIN STATE LOG ---- mDNSResponder mDNSResponder-258.18 (Jan 18 2011 20:25:03)

Apr 30 16:40:45 SVWS106PM1 mDNSResponder[18]: Timenow 0xBB6B3210 (-1150602736)

Apr 30 16:40:45 SVWS106PM1 mDNSResponder[18]: ------------ Cache -------------

Apr 30 16:40:45 SVWS106PM1 mDNSResponder[18]: Slt Q TTL if U Type rdlen

Apr 30 16:40:45 SVWS106PM1 mDNSResponder[18]: 21 * 303 -U- - PTR 0 db._dns-sd._udp.0.178.168.192.in-addr.arpa. PTR

Apr 30 16:40:45 SVWS106PM1 mDNSResponder[18]: 25 * 217 -U- - PTR 0 lb._dns-sd._udp.0.178.168.192.in-addr.arpa. PTR

Apr 30 16:40:45 SVWS106PM1 mDNSResponder[18]: 31 * 425 -U- - PTR 0 lb._dns-sd._udp.socal.rr.com. PTR

Apr 30 16:40:45 SVWS106PM1 mDNSResponder[18]: 61 * 357 -U- - PTR 0 b._dns-sd._udp.0.178.168.192.in-addr.arpa. PTR

Apr 30 16:40:45 SVWS106PM1 mDNSResponder[18]: 69 * 332 -U- - PTR 0 r._dns-sd._udp.0.178.168.192.in-addr.arpa. PTR

Apr 30 16:40:45 SVWS106PM1 mDNSResponder[18]: 90 * 4480 vmnet1 + PTR 32 _http._tcp.local. PTR Administrator._http._tcp.local.

Apr 30 16:40:45 SVWS106PM1 mDNSResponder[18]: 90 * 4480 vmnet8 + PTR 32 _http._tcp.local. PTR Administrator._http._tcp.local.

Apr 30 16:40:45 SVWS106PM1 mDNSResponder[18]: 90 * 4480 en1 + PTR 32 _http._tcp.local. PTR Administrator._http._tcp.local.

Apr 30 16:40:45 SVWS106PM1 mDNSResponder[18]: 92 * 57 -U- - PTR 0 db._dns-sd._udp.0.1.168.192.in-addr.arpa. PTR

Apr 30 16:40:45 SVWS106PM1 mDNSResponder[18]: 100 * 57 -U- - PTR 0 db._dns-sd._udp.0.5.168.192.in-addr.arpa. PTR

Apr 30 16:40:45 SVWS106PM1 mDNSResponder[18]: 124 * 128 -U- - PTR 0 dr._dns-sd._udp.0.1.168.192.in-addr.arpa. PTR

Apr 30 16:40:45 SVWS106PM1 mDNSResponder[18]: 131 * 683 -U- - TXT 0 cf._dns-sd._udp.socal.rr.com. TXT

Apr 30 16:40:45 SVWS106PM1 mDNSResponder[18]: 132 * 357 -U- - PTR 0 dr._dns-sd._udp.0.5.168.192.in-addr.arpa. PTR

Apr 30 16:40:45 SVWS106PM1 mDNSResponder[18]: 161 * 720 -U- - PTR 0 dr._dns-sd._udp.socal.rr.com. PTR

Apr 30 16:40:45 SVWS106PM1 mDNSResponder[18]: 164 * 714 -U- - PTR 0 r._dns-sd._udp.socal.rr.com. PTR

Apr 30 16:40:45 SVWS106PM1 mDNSResponder[18]: 177 * 4480 vmnet1 + PTR 28 _smb._tcp.local. PTR SVWS106PM1._smb._tcp.local.

Apr 30 16:40:45 SVWS106PM1 mDNSResponder[18]: 177 * 4480 vmnet8 + PTR 28 _smb._tcp.local. PTR SVWS106PM1._smb._tcp.local.

Apr 30 16:40:45 SVWS106PM1 mDNSResponder[18]: 177 * 4480 en1 + PTR 28 _smb._tcp.local. PTR SVWS106PM1._smb._tcp.local.

Apr 30 16:40:45 SVWS106PM1 mDNSResponder[18]: 197 * 262 -U- - TXT 0 cf._dns-sd._udp.0.1.168.192.in-addr.arpa. TXT

Apr 30 16:40:45 SVWS106PM1 mDNSResponder[18]: 205 * 287 -U- - TXT 0 cf._dns-sd._udp.0.5.168.192.in-addr.arpa. TXT

Apr 30 16:40:45 SVWS106PM1 mDNSResponder[18]: 247 * 693 -U- - PTR 0 b._dns-sd._udp.socal.rr.com. PTR

Apr 30 16:40:45 SVWS106PM1 mDNSResponder[18]: 277 * 357 -U- - PTR 0 dr._dns-sd._udp.0.178.168.192.in-addr.arpa. PTR

Apr 30 16:40:45 SVWS106PM1 mDNSResponder[18]: 306 * 274 -U- - TXT 0 cf._dns-sd._udp.0.178.168.192.in-addr.arpa. TXT

Apr 30 16:40:45 SVWS106PM1 mDNSResponder[18]: 322 * 82 -U- - PTR 0 db._dns-sd._udp.socal.rr.com. PTR

Apr 30 16:40:45 SVWS106PM1 mDNSResponder[18]: 370 * 235 -U- - PTR 0 lb._dns-sd._udp.0.1.168.192.in-addr.arpa. PTR

Apr 30 16:40:45 SVWS106PM1 mDNSResponder[18]: 378 * 57 -U- - PTR 0 lb._dns-sd._udp.0.5.168.192.in-addr.arpa. PTR

Apr 30 16:40:45 SVWS106PM1 mDNSResponder[18]: 428 * 263 -U- - PTR 0 b._dns-sd._udp.0.1.168.192.in-addr.arpa. PTR

Apr 30 16:40:45 SVWS106PM1 mDNSResponder[18]: 429 * 235 -U- - PTR 0 r._dns-sd._udp.0.1.168.192.in-addr.arpa. PTR

Apr 30 16:40:45 SVWS106PM1 mDNSResponder[18]: 480 * 357 -U- - PTR 0 b._dns-sd._udp.0.5.168.192.in-addr.arpa. PTR

Apr 30 16:40:45 SVWS106PM1 mDNSResponder[18]: 480 4480 vmnet1 + TXT 15 SVWS106PM1._device-info._tcp.local. TXT model=iMac11,3

Apr 30 16:40:45 SVWS106PM1 mDNSResponder[18]: 480 4480 vmnet8 + TXT 15 SVWS106PM1._device-info._tcp.local. TXT model=iMac11,3

Apr 30 16:40:45 SVWS106PM1 mDNSResponder[18]: 480 4480 en1 + TXT 15 SVWS106PM1._device-info._tcp.local. TXT model=iMac11,3

Apr 30 16:40:45 SVWS106PM1 mDNSResponder[18]: 481 * 252 -U- - PTR 0 r._dns-sd._udp.0.5.168.192.in-addr.arpa. PTR

Apr 30 16:40:45 SVWS106PM1 mDNSResponder[18]: Cache currently contains 60 entities; 30 referenced by active questions

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Answer 4

Secretariat Author

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Apr 30, 2011 5:09 PM in response to TeenTitan

If you type:

dscacheutil -flushcache

killall -INFO mDNSResponder

Shouldn't your cache be completely emptied out? Why does the mDNSResponder still hold onto PTR and TXT records? I don't get it.

If you type the following (in Windows), all entries are removed from the cache:

ipconfig /flushdns

ipconfig /displaydns

I am trying to learn why there are 60 entries in my DNS cache after I flush it.

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Answer 5

TeenTitan

Level 4

2,640 points

Apr 30, 2011 4:32 PM in response to Secretariat

what is the exact message your seeing in the console?

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Answer 6

TeenTitan

Level 4

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Apr 30, 2011 8:25 PM in response to Secretariat

That could be useful. Say if your actively connected to a .local device, and while connected you flush the cache.

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Answer 7

Secretariat Author

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Apr 30, 2011 9:05 PM in response to TeenTitan

That's true.

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Answer 8

Secretariat Author

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Apr 30, 2011 5:00 PM in response to TeenTitan

I receive less entries in the cache once I disconnect the network cable, but I still receive 12 entries (below):

Apr 30 16:58:32 SVWS106PM1 mDNSResponder[18]: SIGHUP: Purge cache

Apr 30 16:58:34 SVWS106PM1 mDNSResponder[18]: ---- BEGIN STATE LOG ---- mDNSResponder mDNSResponder-258.18 (Jan 18 2011 20:25:03)

Apr 30 16:58:34 SVWS106PM1 mDNSResponder[18]: Timenow 0xBB7B8256 (-1149533610)

Apr 30 16:58:34 SVWS106PM1 mDNSResponder[18]: ------------ Cache -------------

Apr 30 16:58:34 SVWS106PM1 mDNSResponder[18]: Slt Q TTL if U Type rdlen

Apr 30 16:58:34 SVWS106PM1 mDNSResponder[18]: 90 * 4498 vmnet1 + PTR 32 _http._tcp.local. PTR Administrator._http._tcp.local.

Apr 30 16:58:34 SVWS106PM1 mDNSResponder[18]: 90 * 4498 vmnet8 + PTR 32 _http._tcp.local. PTR Administrator._http._tcp.local.

Apr 30 16:58:34 SVWS106PM1 mDNSResponder[18]: 90 * 4498 lo0 + PTR 32 _http._tcp.local. PTR Administrator._http._tcp.local.

Apr 30 16:58:34 SVWS106PM1 mDNSResponder[18]: 177 * 4498 vmnet1 + PTR 28 _smb._tcp.local. PTR SVWS106PM1._smb._tcp.local.

Apr 30 16:58:34 SVWS106PM1 mDNSResponder[18]: 177 * 4498 vmnet8 + PTR 28 _smb._tcp.local. PTR SVWS106PM1._smb._tcp.local.

Apr 30 16:58:34 SVWS106PM1 mDNSResponder[18]: 177 * 4498 lo0 + PTR 28 _smb._tcp.local. PTR SVWS106PM1._smb._tcp.local.

Apr 30 16:58:34 SVWS106PM1 mDNSResponder[18]: 480 4498 vmnet1 + TXT 15 SVWS106PM1._device-info._tcp.local. TXT model=iMac11,3

Apr 30 16:58:34 SVWS106PM1 mDNSResponder[18]: 480 4498 vmnet8 + TXT 15 SVWS106PM1._device-info._tcp.local. TXT model=iMac11,3

Apr 30 16:58:34 SVWS106PM1 mDNSResponder[18]: 480 4498 lo0 + TXT 15 SVWS106PM1._device-info._tcp.local. TXT model=iMac11,3

Apr 30 16:58:34 SVWS106PM1 mDNSResponder[18]: Cache currently contains 12 entities; 6 referenced by active questions

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Answer 9

TeenTitan

Level 4

2,640 points

Apr 30, 2011 7:04 PM in response to Secretariat

Mac OS X v10.6: Disabling mDNSResponder will disable DNS:

Mac OS X v10.6 uses the mDNSResponder process for unicast DNS (Domain Name System) functions, as well as Bonjour functions.

dscacheutil -flushcache is clearing the cache on an active service. So soon as the command has been processed new entries can added. If you look at the entries are for lo0, vmnet1 & vmnet8. All of witch seem to be .local traffic. ".local" traffic is usually associated with bonjour traffic. Aka the computer uses bonjour to find other devices on the local netwok(s).

Did you leave airport on?

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