I want to see and dump DNS cache entries in DNsmasq.How can i do?
port=53
resolv-file=/etc/resolv.dnsmasq.conf
log-queries
log-facility=/root/dnsmasq.log
cache-size=1
#local-ttl=3600
log-async=50
clear-on-reload
interface=GE2
bind-interfaces
The utility dnsmasq maintains an in-memory cache. You could restart the utility with the -q flag to log the results to /var/log/syslog.
Refer the following link, for full details:
https://unix.stackexchange.com/questions/162973/how-to-measure-dns-cache-efficiency-cached-items/163075#163075
Related
I am getting this error when i am trying to restart my clickhouse server.
Failed to start clickhouse-server.service: The name org.freedesktop.PolicyKit1 was not provided by any .service files
See system logs and 'systemctl status clickhouse-server.service' for details.
Upon further inspection of server. We noticed that Log directory was full. After flushing the logs clickhouse server restarted normally. But the error message made no sense cite the actual problem. then what is this error pointing to ? Pls enlight
org.freedesktop.PolicyKit1 , is like sudo but for systemd. It should be enabled for systemd to work. Resolved it by accessing ec2 superuser privelage.
sudo su
I expect to be able to resolve the DNS name www.foobar.dev using a DNS server that's running in a VM on my OS/X (High Sierra) system because I have created an /etc/resolver/dev file containing the following one line: (specifying the VM's virtual address)
nameserver ww.xx.yy.zz
... but dig www.foobar.dev continues to consult the Internet nameserver,
while dig #ww.xx.yy.zz www.foobar.dev successfully retrieves the entry from the VM's DNS.
I've used the dscacheutil command to be sure that an errant entry is not in the DNS resolver cache.
So, why isn't the presence of an /etc/resolver/dev file with the specified contents sufficient to direct "anything.dev" to the specified DNS server?
Interestingly – sometimes it seems to work. Also, the command scutil --dns produces the following expected entry, which seems to indicate that the /etc/resolver/dev file is being detected!
resolver #8
domain : dev
nameserver[0] : ww.xx.yy.zz
flags : Request A records
reach : 0x00020002 (Reachable,Directly Reachable Address)
It's probably working fine, you're just testing it wrong. dig (and host and nslookup) don't use the system resolver, nor do they fully implement the system resolver's lookup policy. As a result, they're useful for testing the DNS system itself, but not for testing how the OS uses DNS. The official way to test the system resolver is dscacheutil (e.g. dscacheutil -q host -a name www.foobar.dev), but that's annoyingly verbose, so I tend to just use ping and look at the IP it reports.
As #GordonDavisson in other answer said - ping command is useful for the system resolver testing. My addition is that it also may fail because of DNS cache. Do not forget to clear it:
sudo killall -HUP mDNSResponder
Better replace /etc/resolver files with true DNS config, as just like /etc/resolv.conf this is all legacy stuff kept only for backward compatibility (and maybe because POSIX requires it?).
Here's how you can do it from command line using scutil, it's really simple.
Of course, there is also a programmatic interface to all this.
See Apple's SystemConfiguration Framework.
I was looking to find the details of the Virtual Machine using govc.
I was able to fetch the details of the instance using govc vm.info, but the result had details of CPU, Memory, IP Address and other not about disk storage, which I can see on vsphere console or by logging into system.
Is there any using govc to find the disk attached to the instance ??
I asked this on govc's Github repo.
You can use:
To get <path/to/vm>, use
govc vm.info vm-name-here
To get all the details of the VM
govc ls -l -json <path/to/vm>
You can also get information about devices using
$ govc device.info -vm VirtualMachineName
I have a host configured into Ambari which no longer exists. Ambari still thinks it's there. When I try to delete it through the UI I get:
400 status code received on DELETE method for API:
/api/v1/clusters/handy091015/hosts/r-hadoopeco-celeryworker-07ac46a4.hbinternal.com/host_components/ZOOKEEPER_CLIENT
Error message: Bad Request
When I try to delete it via the api, with the command below, I get the same host information as with a GET:
curl -H "X-Requested-By: ambari" -DELETE http://admin:admin#ambari.handy-internal.com//api/v1/clusters/handy091015/hosts/r-hadoopeco-celeryworker-07ac46a4.hbinternal.com
I have tried the instructions here to no avail:
https://cwiki.apache.org/confluence/display/AMBARI/Using+APIs+to+delete+a+service+or+all+host+components+on+a+host
My question is: how do I get Ambari to no longer know about/try to do things with this host.
I am not able to reproduce your behaviour with Ambari 2.1.2 and HDP 2.3 stack.
Limitation:
Note that host removing is supported only for hosts with no master components, so if they are present, then deleting is not possible.
Options:
Try to do ambari-server restart, sometimes it have intermittent issues
If this is an option, I recomend you to do ambari-server reset and install it from scratch. If you don't have much setup, it will save your time probably.
If not, you may want to post ambari-server.log file additionally. This may help to debug the core issue
Another option - just ignore that host, it will not do much harm to you. You can move it to maintenance mode, that will ease cluster operation.
I am trying to build and install membase from source tarball. The steps I followed are:
Un-archive the tar membase-server_src-1.7.1.1.tar.gz
Issue make (from within the untarred folder)
Once done, I enter into directory install/bin and invoke the script membase-server.
This starts up the server with a message:
The maximum number of open files for the membase user is set too low.
It must be at least 10240. Normally this can be increased by adding
the following lines to /etc/security/limits.conf:
Tried updating limits.conf as suggested, but no luck it continues to pop up the same message and continues booting
Given that the server is started I tried accessing memcached over port 11211, but I get a connection refused message. Then figured out (netstat) that memcached is listening to 11210 and tried telneting to port 11210, unfortunately the connection is closed as soon as I issue the following commands
stats
set myvar 0 0 5
Note: I am not getting any output from the commands above {Yes: stats did not show anything but still I issued set.}
Could somebody help me build and install membase from source? Also why is memcached listening to 11210 instead of 11211?
It would be great if somebody could also give me a step-by-step guide which I can follow to build from source from Git repository (I have not used autoconf earlier).
P.S: I have tried installing from binaries (debian package) on the same machines and I am able to successfully install and telnet. Hence not sure why is build from source not working.
You can increase the number of file descriptors on your machine by using the ulimit command. Try doing (you might need to use sudo as well):
ulimit -n 10240
I personally have this set in my .bash_rc so that whenever I start my terminal it is always set for me.
Also, memcached listens on port 11210 by default for Membase. This is done because Moxi, the memcached proxy server, listens on port 11211. I'm also pretty sure that the memcached version used for Membase only listens for the binary protocol so you won't be able to successfully telnet to 11210 and have commands work correctly. Telneting to 11211 (moxi) should work though.