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- The Support and Recovery Assistant tool will run a series of diagnostic tests on your computer and help you set up a new profile, or resolve other issues. If any of the tests fails, it will provide suggested solutions to get your problem solved.
- Data Recovery Guru, EaseUS Data Recovery Wizard, and Prosoft Data Rescue are among the more acclaimed data recovery tools for Mac. All of these programs will scan your disk and create lists of deleted files—often sorted by different file types.
- Network Stuff is a Free Portable Network Tool that can be used to perform various network diagnostic functions such as Telnet, Ping, Traceroute, Whois, DNS resolver, retreive MAC address, retreive IP address, view TCP/UDP/ICMP stats and much more. A very handy portable network diagnostic tool to add to your arsenal.
- Winclone is a tool from Twocanoes Software that creates a clone of the Windows Boot Camp partition for recovery or migration to another Mac. (Pricing starts at $29.99 for an individual license.
- Resolve DNS for host oscdn.apple.com and contact it on port 80 (HTTP) and port 443 (HTTPS) These hostnames might resolve to different IP addresses each time that you use them. When macOS Recovery connects to the server, it sends information that identifies the hardware model of the computer.
This is the best recovery tool that can help the users to recover their lost data from FAT volume on Mac. This application allows a easy recovery of files from a FAT partition, which was either deleted or formatted.
Some of my coworkers are having troubles on their Macs - DNS resolution does not work under Mac OS X. They're running Snow Leopard 10.6.8. They can use DNS in a Windows 7 virtual machine (VMware Fusion 3.1.3) running under OS X. The computers are 15' MacBook Pros, early 2011 model.
Things they've tried that have not worked:
- turning airport on/off
- rebooting
- using wired connection instead wifi
- deleting connection credentials and adding it again
- turning off Mac firewall
- using fixed static IP
- manually setting DNS servers
- restarting mDNSResponder
- the fixes from this other question
EDIT response Martín's answer:
• Can you ping the DNS you want to use?
• What is/are the IP address(es) of the DNS(s) you want to use?
This is a company DNS server that is given with DHCP, it works well forother people. I've also tried Google's 8.8.4.4 and 205.171.3.65 (which I found from GRC's DNS Benchmark to be the fastest).
• Have you tried using 8.8.8.8 (google) or any of the OpenDNS 208.67.222.222 or 208.67.220.220?
It doesn't work, see Google Chrome output:
The server at www.apple.com can't be found, because the DNS lookup failed. DNS is the network service that translates a website's name to its Internet address. This error is most often caused by having no connection to the Internet or a misconfigured network. It can also be caused by an unresponsive DNS server or a firewall preventing Google Chrome from accessing the network.
• Can you ping those hosts?
• creating a blank user
A guest user account was created, the DNS issue was still there when usingthe guest account.
• nslookup and dig both work fine
• also flushing the DNS cache was done but it didn't help
EDIT 2:
Community♦
CajunLukeCajunLuke15.7k66 gold badges4747 silver badges7070 bronze badges
22 Answers
It turns out the solution was to bounce mDNSResponder:
This was obtained by a different coworker from this Server Fault question.
OS X 10.10.0 – 10.10.3, Yosemite
Apparently, mDNSResponder doesn't exist in Yosemite (OS X 10.10). You can restart descoveryd instead to fix these issues.
OS X 10.10.4+, Yosemite
In OSX 10.10.4 the mDNSResponder has been reintroduced. So use the first one will work again.
Community♦
CajunLukeCajunLuke15.7k66 gold badges4747 silver badges7070 bronze badges
Actually, I think you might want to use
![Iphone Iphone](https://www.simpletelly.com/wp-content/uploads/2014/09/apple-ipad-set-dns-addresses.jpg)
These commands use the dynamic store in configd, as opposed to the flatfiles in /etc, which often are only read in single user mode and for non networked systems.
chiggsychiggsy2,19811 gold badge2020 silver badges3333 bronze badges
Name resolution under OSX (and UNIX in general) is taken from the IP addresses of the DNSs in the file located in /etc/resolv.conf (which OS X automatically generates as far as I can remember).
Since you've tried virtually anything that comes to my mind, I'd like to ask you:
- Can you ping the DNS you want to use?
- What is/are the IP address(es) of the DNS(s) you want to use?
- Have you tried using 8.8.8.8 (google) or any of the OpenDNS 208.67.222.222 or 208.67.220.220?
- Can you ping those hosts?
Finally, a usually nice test consists of creating a blank user and seeing if that new user exhibits the same problem. If it doesn't, then you can start digging what your current user has that could be causing the issue; if it also fails, then you know this is something more 'system' related.
Also take a look around the Console to see if you can spot something that may be related (and would like to paste around here).
Last but not least, your Mac comes with two important DNS commands,
nslookup
and dig
. So to resolve www.apple.com using google's server, you'd type:
nslookup 'host to resolve' 'DNS server to use'. E.g.:
NSLookup is an old command (that was supposed to be deprecated some years ago and replaced by DIG, but its easy to use syntax was too good to kill I guess.), its 'replacement' is
dig
, a much more powerful command, whose syntax is more crazy.To perform the same query, you'd type:
dig @8.8.8.8 www.apple.com
ANd here's the output:
As you can see, dig is much more 'verbose' (which is good to debug what the heck is going on).The power of dig comes from the fact that you can specify what type of query you want to perform (Among other things).
In any case, let us know the exact outputs of these commands.
Martin MarconciniMartin Marconcini20.7k11 gold badge4949 silver badges8181 bronze badges
I've experienced the same problem… And while restarting mDNSResponder does seem to 'work', restarting it a couple of times every hour sort of sucks.
So, for now, I've 'solved' the problem by running dnsmasq locally. To do that:
- Build dnsmasq (download the tgz and
make
orbrew install dnsmasq
) - Put this in a
dnsmasq.conf
file: - Put this in a
resolv.conf
file that is in the same directory as thednsmasq.conf
file (nb: not/etc/resolv.conf
): - Run
dnsmasq
withsudo dnsmasq --no-daemon --log-queries -C dnsmasq.conf
. The output should look something like: - Open Network Preferences and make sure that
127.0.0.1
is the only DNS server (network preferences -> advanced -> DNS -> add 127.0.0.1)
Things should begin to work nicely again.
Once things are working, you can run
techrafdnsmasq
without the --no-daemon
and --log-queries
options, so it will start in the background and you don't need to keep a Terminal window open.2,84077 gold badges1616 silver badges3232 bronze badges
David WoleverDavid Wolever93811 gold badge1010 silver badges1919 bronze badges
I had the same exact same symptoms (and spend a while troubleshooting) but I was able to resolve it when I realized that I messed with
/System/Library/LaunchDaemons/com.apple.mDNSResponder.plist
and what I did was somehow interpreted as malformed. I restored from a backup and the machine was able resolve hostnames again.Before coming to the solution, I also realized that I was able to browse the internet if I used a SOCKS5 proxy through
techrafssh -D
and tried DNS lookups through the tunnel.2,84077 gold badges1616 silver badges3232 bronze badges
freezedpeanutsfreezedpeanuts
I had a very, very similar issue, except the symptoms were slightly different.
My user could not resolve any name (local NAS, Google etc) but a guest user on the same iMac (OS X 10.7.4) worked fine.
Flushing and restarting mDNSResponder as mentioned worked for a while. Whilst it would remain working when the iMac was put in sleep mode, it would always fail once rebooted.
When the flush/restart stopped working I looked for other reasons/solutions and I found that it was related to my firewall. I don't know what in my (OS X) firewall settings was causing it, but if I restored the firewall setting it worked.
To restore the default settings I used:
Obviously any custom rules will have been removed with this restore.
I wanted to share my version of this issue as it's been causing me grief on and off for months and this post is the best collection of possible solutions on the net!
CajunLuke15.7k66 gold badges4747 silver badges7070 bronze badges
Simon C SmithSimon C Smith
I hit this problem on Yosemite (10.10). Turns out that a key daemon,
discoveryd
, was killed off as it was consuming too much CPU.Strangely rebooting didn't cause it to be restarted.
I manually restarted the service with:
and now all is well.
Brian de AlwisBrian de Alwis
I am having the same problem with 10.6.8. The first trip to an Apple Store resulted in system restore. But, after that, DNS broke again while I was overseas and didn't have a system DVD with me. At that time I found this thread and deleted
/System/Library/LaunchDaemons/com.apple.mDNSResponder.plist
per @freezedpeanuts and @Tom Thorogood.It fixed the problem, but, amazingly, DNS broke for the third time couple of days later. I hunted down a system image of 10.6.3 and:
- Copied
/System/Library/LaunchDaemons/com.apple.mDNSResponder.plist
from the system image. sudo chown root /System/Library/LaunchDaemons/com.apple.mDNS*
- Rebooted
That fixed the problem.
It breaks periodically for me now (once a month or so), and the restore procedure is down to the steps above, except instead of rebooting you can:
sudo launchctl load -w /System/Library/LaunchDaemons/com.apple.mDNSResponder.plist
DKrootDKroot
Please note to anyone still having issues, you might have to remove any public DNS servers until cache is cleared.
Dustin MatlockDustin Matlock
I had seemingly the same problem as the OP.Using the tool networksetup I found that for the given network name, some wrong DNS was configured:
listed 192.168.0.1 as DNS. Using scutil --dns I've got comparable results, listing that resolver #2 used nameserver[0] : 192.168.0.1.
Using the command
I was able to reconfigure the DNS for the given network and resolve names of local and global machines when connected to the VPN.
rexfordrexford
In my case, everything else was fine: mDNSResponder was running and working,
host
/nslookup
worked, both /etc/resolv.conf
and networksetup
reported the correct DNS servers, etc. Despite all that, DNS resolution in general (e.g. with ping
) inevitably stopped working at some point a few hours after boot.This specific problem may be somewhat unlikely, but I'm going to document it here as an answer anyway.
I only noticed when the machine started slowing down, but there were a lot of identical processes running.
sensu-client
, specifically.We had it configured in launchd with this plist file:
The
-b
flag to sensu-client
makes it fork to the background, acting as a daemon. However, all launchd
sees is that the original process terminated, so (in accordance with the KeepAlive
flag) it restarts it. This leaves thousands of forked processes in the background, and even then launchd will be none the wiser to the fact that it is running.I believe that these several thousand processes (all
sensu-client
, the software we had written a launchd config for) may have been simultaneously making requests to mDNSResponder, effectively resulting in a local denial of service of the DNS cache. Killing these processes and fixing the plist given to launchd eventually solved the problem.The plist fix was just to remove the
-b
(background / daemonise) flag from the sensu-client invocation. Note that this is not sensu's fault; this plist was written by a former system administrator at this company.Score_UnderScore_Under
Here are few advanced commands which can help to troubleshoot the DNS problem:
- Run
dig
to list the root name servers. - Run
dig example.com
to run DNS lookup forexample.com
domain. - List your hardware ports by:
networksetup -listallhardwareports
. - Check output of the DHCP/BOOTP packet that the client accepted from the DHCP/BOOTP server by:
ipconfig getpacket en0
. - Check your DNS configuration by:
scutil --dns
. - Verify that
mDNSResponder
process is running by:ps wuax | grep mDNSResponder
. - Flush ARP translation entries by:
arp -ad
(runman arp
for help).source
To debug
mDNSResponder
process, the following command may help:The above command will send
kenorbkenorbSIGINFO
signal to the process which will dump debugging details into log output which can be read and analysed.7,66299 gold badges5454 silver badges103103 bronze badges
Turning Wi-Fi off and on again helped.
MacBook Pro with 10.9.1
Especially if you turn off wifi and then reboot. The extra delay and starting with no IP/network connection ensure the request to rejoin the network has better chances to succeed.
Dns Recovering Tools For Mac
bmike♦168k4646 gold badges304304 silver badges662662 bronze badges
Lukasz MadonLukasz Madon
This probably won't help anybody, but in case, I accidentally some time ago, created a file in the folder, when a DNS was down for a particular domain:
/etc/resolver/
and this was preventing a specific name from ever being resolved, two years later.
JérémieJérémie
Unfortunately none of this helped me, and turned out after an hour of trying to figure it out and beating my head against the coffee table .. something, somehow, somewhere ... removed the
/System/Library/LaunchDaemons/com.apple.mDNSResponder.plist
file, and was the reason I had this problem.Realized this when I saw this error message:
/System/Library/LaunchDaemons/com.apple.mDNSResponder.plist: No such file or directory
Here's a copy of a version from El Capitan:https://gist.github.com/tripflex/e7147690d1768dc74b1dd626614573c0
Here's the code from that gist:
sMylessMyles
As it turns out, to solve the problem you have to configure a search domain and add it to the search domain field under System Preferences dns configuration. Basically, the search domain will work sort of the way that .local does, but instead it will be .
You have to set up your search domain as a master zone in your dns server for this to work.
YeisonYeison
I've a similar problem with finding the host server. We have 21 iMacs running from the Server (El Capitan, recently upgraded) and only one won't bind. The fix is usually pretty simple through Users and Groups in SysPref. Deleting the host server and re-binding, finding the available server in the dropdown option, but for some unknown reason the server is listed as
unkown-00-00-12-34-56-78.home
, which I've found is the MAC address of the server.I ran this in terminal:and
returned to bind to the server in SysPref and the correct server name option briefly appeared and then changed back to 'unkown-00-00-12-34-56-78.home' right in front of my eyes!
cwj73cwj73
When following commands from accepted answer:
you may run into warning:
Operation not permitted while System Integrity Protection is engaged
You need to turn it off. Whole instruction here:https://www.howtogeek.com/230424/how-to-disable-system-integrity-protection-on-a-mac-and-why-you-shouldnt/
andilabsandilabs47433 gold badges77 silver badges1919 bronze badges
In my case I had OpenDNS installed in the past and it wasn't removed cleanly. There were several dns related processes running such as DNSdnscrypt-proxy. I couldn't force quit them in Activity Monitor but I was able to stop them from starting up on restart by removing the .plist file in Library/LaunchDaemons.
HaoHao
Go to Settings -> Network -> Advanced -> DNS. Then make literally any changes at all to DNS (reorder your DNS entries, for example). Then click 'Ok' followed by 'Apply' on the next screen. Don't be fooled into thinking that the particular change you made was significant; it's the magic of the 'Apply' button.
weberc2weberc2
What worked for me was removing all the server entries from DNS Servers and Search Domains from:
System Preferences → Network → Advanced... → DNS
Nimesh Neema24.5k99 gold badges6363 silver badges9595 bronze badges
MarceloMarcelo
After upgrading from Snow Leopard on an old Mac Book to Mountain Lion, the system could not resolve DNS. Flushing, restart, nothing helped. Changing WiFi to a different Access point (my phone) helped.
Mountain Lion adds a new client field to the DHCP network settings. Filling in this field seemed to make the wifi access point happy. Leaving it blank meant nothing was getting thru, even though the wifi connection seemed to succeed.
xt1xt1