How shall I understand the format of `/etc/resolv.conf`?
How shall I understand the format of /etc/resolv.conf
?
$ cat /etc/resolv.conf
# This file is managed by man:systemd-resolved(8). Do not edit.
#
# This is a dynamic resolv.conf file for connecting local clients to the
# internal DNS stub resolver of systemd-resolved. This file lists all
# configured search domains.
#
# Run "systemd-resolve --status" to see details about the uplink DNS servers
# currently in use.
#
# Third party programs must not access this file directly, but only through the
# symlink at /etc/resolv.conf. To manage man:resolv.conf(5) in a different way,
# replace this symlink by a static file or a different symlink.
#
# See man:systemd-resolved.service(8) for details about the supported modes of
# operation for /etc/resolv.conf.
nameserver 127.0.0.53
search fios-router.home
Manpage of /etc/resolve.conf says
The different configuration options are:
nameserver Name server IP address
Internet address of a name server that the resolver should
query...
So does nameserver 127.0.0.53
mean that my local machine is running a DNS server whose IP address is 127.0.0.53? How can I find out its process?
domain Local domain name.
Most queries for names within this domain can use short names
relative to the local domain. If set to '.', the root domain
is considered. If no domain entry is present, the domain is
determined from the local hostname returned by gethostname(2);
the domain part is taken to be everything after the first '.'.
Finally, if the hostname does not contain a domain part, the
root domain is assumed.
What does this part mean? The above just mentions what values that can be set to something, and does not explain what this part in /etc/resolv.conf means. Why does my /etc/resolv.conf not have this part?
search Search list for host-name lookup.
The search list is normally determined from the local domain
name; by default, it contains only the local domain name.
What does this part mean? What does search fios-router.home
in my /etc/resolv.conf mean?
Thanks.
dns resolv.conf
add a comment |
How shall I understand the format of /etc/resolv.conf
?
$ cat /etc/resolv.conf
# This file is managed by man:systemd-resolved(8). Do not edit.
#
# This is a dynamic resolv.conf file for connecting local clients to the
# internal DNS stub resolver of systemd-resolved. This file lists all
# configured search domains.
#
# Run "systemd-resolve --status" to see details about the uplink DNS servers
# currently in use.
#
# Third party programs must not access this file directly, but only through the
# symlink at /etc/resolv.conf. To manage man:resolv.conf(5) in a different way,
# replace this symlink by a static file or a different symlink.
#
# See man:systemd-resolved.service(8) for details about the supported modes of
# operation for /etc/resolv.conf.
nameserver 127.0.0.53
search fios-router.home
Manpage of /etc/resolve.conf says
The different configuration options are:
nameserver Name server IP address
Internet address of a name server that the resolver should
query...
So does nameserver 127.0.0.53
mean that my local machine is running a DNS server whose IP address is 127.0.0.53? How can I find out its process?
domain Local domain name.
Most queries for names within this domain can use short names
relative to the local domain. If set to '.', the root domain
is considered. If no domain entry is present, the domain is
determined from the local hostname returned by gethostname(2);
the domain part is taken to be everything after the first '.'.
Finally, if the hostname does not contain a domain part, the
root domain is assumed.
What does this part mean? The above just mentions what values that can be set to something, and does not explain what this part in /etc/resolv.conf means. Why does my /etc/resolv.conf not have this part?
search Search list for host-name lookup.
The search list is normally determined from the local domain
name; by default, it contains only the local domain name.
What does this part mean? What does search fios-router.home
in my /etc/resolv.conf mean?
Thanks.
dns resolv.conf
You can runnetstat -up
as root to see if and who is listening on port 53 of::
or0.0.0.0
or127.0.0.53
.
– eckes
5 hours ago
freedesktop.org/software/systemd/man/… you might be in a systemd-resolved manging mode
– 炸鱼薯条德里克
2 hours ago
Just note that the netmask for localhost is255.0.0.0
, a /8. So127.0.0.53
is also localhost.
– Lenne
2 hours ago
@eckes netstat -up shows nothing is listening
– Tim
9 mins ago
add a comment |
How shall I understand the format of /etc/resolv.conf
?
$ cat /etc/resolv.conf
# This file is managed by man:systemd-resolved(8). Do not edit.
#
# This is a dynamic resolv.conf file for connecting local clients to the
# internal DNS stub resolver of systemd-resolved. This file lists all
# configured search domains.
#
# Run "systemd-resolve --status" to see details about the uplink DNS servers
# currently in use.
#
# Third party programs must not access this file directly, but only through the
# symlink at /etc/resolv.conf. To manage man:resolv.conf(5) in a different way,
# replace this symlink by a static file or a different symlink.
#
# See man:systemd-resolved.service(8) for details about the supported modes of
# operation for /etc/resolv.conf.
nameserver 127.0.0.53
search fios-router.home
Manpage of /etc/resolve.conf says
The different configuration options are:
nameserver Name server IP address
Internet address of a name server that the resolver should
query...
So does nameserver 127.0.0.53
mean that my local machine is running a DNS server whose IP address is 127.0.0.53? How can I find out its process?
domain Local domain name.
Most queries for names within this domain can use short names
relative to the local domain. If set to '.', the root domain
is considered. If no domain entry is present, the domain is
determined from the local hostname returned by gethostname(2);
the domain part is taken to be everything after the first '.'.
Finally, if the hostname does not contain a domain part, the
root domain is assumed.
What does this part mean? The above just mentions what values that can be set to something, and does not explain what this part in /etc/resolv.conf means. Why does my /etc/resolv.conf not have this part?
search Search list for host-name lookup.
The search list is normally determined from the local domain
name; by default, it contains only the local domain name.
What does this part mean? What does search fios-router.home
in my /etc/resolv.conf mean?
Thanks.
dns resolv.conf
How shall I understand the format of /etc/resolv.conf
?
$ cat /etc/resolv.conf
# This file is managed by man:systemd-resolved(8). Do not edit.
#
# This is a dynamic resolv.conf file for connecting local clients to the
# internal DNS stub resolver of systemd-resolved. This file lists all
# configured search domains.
#
# Run "systemd-resolve --status" to see details about the uplink DNS servers
# currently in use.
#
# Third party programs must not access this file directly, but only through the
# symlink at /etc/resolv.conf. To manage man:resolv.conf(5) in a different way,
# replace this symlink by a static file or a different symlink.
#
# See man:systemd-resolved.service(8) for details about the supported modes of
# operation for /etc/resolv.conf.
nameserver 127.0.0.53
search fios-router.home
Manpage of /etc/resolve.conf says
The different configuration options are:
nameserver Name server IP address
Internet address of a name server that the resolver should
query...
So does nameserver 127.0.0.53
mean that my local machine is running a DNS server whose IP address is 127.0.0.53? How can I find out its process?
domain Local domain name.
Most queries for names within this domain can use short names
relative to the local domain. If set to '.', the root domain
is considered. If no domain entry is present, the domain is
determined from the local hostname returned by gethostname(2);
the domain part is taken to be everything after the first '.'.
Finally, if the hostname does not contain a domain part, the
root domain is assumed.
What does this part mean? The above just mentions what values that can be set to something, and does not explain what this part in /etc/resolv.conf means. Why does my /etc/resolv.conf not have this part?
search Search list for host-name lookup.
The search list is normally determined from the local domain
name; by default, it contains only the local domain name.
What does this part mean? What does search fios-router.home
in my /etc/resolv.conf mean?
Thanks.
dns resolv.conf
dns resolv.conf
edited 9 hours ago
Tim
asked 9 hours ago
TimTim
26.8k77258469
26.8k77258469
You can runnetstat -up
as root to see if and who is listening on port 53 of::
or0.0.0.0
or127.0.0.53
.
– eckes
5 hours ago
freedesktop.org/software/systemd/man/… you might be in a systemd-resolved manging mode
– 炸鱼薯条德里克
2 hours ago
Just note that the netmask for localhost is255.0.0.0
, a /8. So127.0.0.53
is also localhost.
– Lenne
2 hours ago
@eckes netstat -up shows nothing is listening
– Tim
9 mins ago
add a comment |
You can runnetstat -up
as root to see if and who is listening on port 53 of::
or0.0.0.0
or127.0.0.53
.
– eckes
5 hours ago
freedesktop.org/software/systemd/man/… you might be in a systemd-resolved manging mode
– 炸鱼薯条德里克
2 hours ago
Just note that the netmask for localhost is255.0.0.0
, a /8. So127.0.0.53
is also localhost.
– Lenne
2 hours ago
@eckes netstat -up shows nothing is listening
– Tim
9 mins ago
You can run
netstat -up
as root to see if and who is listening on port 53 of ::
or 0.0.0.0
or 127.0.0.53
.– eckes
5 hours ago
You can run
netstat -up
as root to see if and who is listening on port 53 of ::
or 0.0.0.0
or 127.0.0.53
.– eckes
5 hours ago
freedesktop.org/software/systemd/man/… you might be in a systemd-resolved manging mode
– 炸鱼薯条德里克
2 hours ago
freedesktop.org/software/systemd/man/… you might be in a systemd-resolved manging mode
– 炸鱼薯条德里克
2 hours ago
Just note that the netmask for localhost is
255.0.0.0
, a /8. So 127.0.0.53
is also localhost.– Lenne
2 hours ago
Just note that the netmask for localhost is
255.0.0.0
, a /8. So 127.0.0.53
is also localhost.– Lenne
2 hours ago
@eckes netstat -up shows nothing is listening
– Tim
9 mins ago
@eckes netstat -up shows nothing is listening
– Tim
9 mins ago
add a comment |
4 Answers
4
active
oldest
votes
Yes, the first part indicates that your system is expecting a nameserver to be listening on localhost
, in this case, specifically 127.0.0.53
.
The second part is a search path that is appended to all searches not ending in a period (.
). If you run, for instance, ssh blah
, DNS will first try to look up blah
, then try looking up blah.fios-router.home
.
Thanks. I never know the local machine is running a DNS server. Can you tell me how to find out its process?
– Tim
9 hours ago
Trypgrep systemd-resolved
orsystemctl status systemd-resolved
.
– telcoM
8 hours ago
@telcoMpgrep systemd-resolved
returns nothing. Doesnameserver 127.0.0.53
really mean the my local machine is running a DNS server?
– Tim
35 mins ago
add a comment |
The search fios-router.home
part is the last resolvable domain, i.e. your router (iirc Verizon).
127.0.0.53 is the IP address of the nameserver, so your assumption is correct.
New contributor
Thanks. (1) What is "a resolvable domain" and what is "the last resolvable domain"? (2) Do you mean my local machine is running a DNS server? Which process is the DNS server?
– Tim
9 hours ago
add a comment |
/etc/resolve.conf
is the main configuration file for the DNS client, so its presence does not imply that you are running a DNS server.
Its primary purpose is to list the IP addresses of DNS servers, in your case:
nameserver 127.0.0.53
- Entries of type
nameserver
tell the host, which DNS server to use. - An entry of type
domain
(if present) tells the system which domain it is in. This allows to be addressed by its host name. (Addition in response to a comment: The hostname is the computer's name in the network. On many systems, you can see the hostname in the command prompt; if not, you can find it by using the commandhostname
.) - An entry of type
search
(if present) would allow computers from different domains to address each other by their respective host names.
The file is nowadays usually generated by NeteworkManager
(for example, on my system, the file starts with the comment "Generated by NetworkManager") or by systemd-resolved
.
systemd-resolved
is a system service that provides network name resolution to local applications. It implements a caching and validating DNS/DNSSEC stub resolver, as well as an LLMNR and MulticastDNS resolver and responder.
Also according to systemd-resolved's manpage, the address 127.0.0.53
is a "local DNS stub listener". On related Stack Exchange sites, there have been questions about how to change this, since the file is /etc/resolv.conf
is automatically generated. See for example
Wrong nameserver set by resolvconf and NetworkManager (Ubuntu SE).
DNS set to systemd's 127.0.0.53 - how to change permanently? (Ubuntu SE).
1
Thanks. (1) "Entries of type nameserver tell the host, which DNS server to use." 127.0.0.53 is an IP of local machine. How is that not contradictory to "its presence does not imply that you are running a DNS server"? (2) "An entry of type domain (if present) tells the system which domain it is in. This allows to be addressed by its host name." What is the difference and relation between a domain (name) and a host name?
– Tim
9 hours ago
1) it is only visible to your local system, not to any other systems; not even within your home network. So it does not serve any others. 2) A hostname might be short (host1
) or fully-qualified (host1.fios-router.home
). In this example, the domain ofhost1.fios-router.home
would befios-router.home
.
– telcoM
8 hours ago
Sols -al /etc/resolv.conf
andcat /etc/resolv.conf
will inform you which program/service is controlling resolv.conf. If you've messed about with your system then you might have a couple of programs competing for control - I had this before with dnsmasq, bind, and systemd-resolved. In addition @Tim, to what telcoM says about your questions: the DNS server and resolver ("stub resolver") can be different, you can pass DNS requests to 127.0.0.53 which pass them to your router for actual DNS (eg it could handle local hosts but pass requests for remote hosts on for full DNS).
– pbhj
6 hours ago
@pbhj "you can pass DNS requests to 127.0.0.53 which pass them to your router for actual DNS." 127.0.0.53 refers to the local machine itself, so why does it pass DNS request to your router ?
– Tim
36 mins ago
add a comment |
resolv.conf
is part of the standard way to resolve a host name to an IP address. It is part of the resolver library.
There are different ways to resolve your host name:
- files (specifically:
/etc/hosts
) - dns
- NIS, NIS+ or yp
The sequence in which they are used is in /etc/nsswitch.conf
. This normally says
hosts: files dns
which means that the resolver library first looks in /etc/hosts
and, if it cannot find it there, will use DNS.
Now DNS will query a DNS server. Which one is determined by /etc/resolv.conf
. In addition, there are a number of additional parameters that you can use to help the DNS reolution, of which search
(Try this domain first for the host) is probably the most used.
add a comment |
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4 Answers
4
active
oldest
votes
4 Answers
4
active
oldest
votes
active
oldest
votes
active
oldest
votes
Yes, the first part indicates that your system is expecting a nameserver to be listening on localhost
, in this case, specifically 127.0.0.53
.
The second part is a search path that is appended to all searches not ending in a period (.
). If you run, for instance, ssh blah
, DNS will first try to look up blah
, then try looking up blah.fios-router.home
.
Thanks. I never know the local machine is running a DNS server. Can you tell me how to find out its process?
– Tim
9 hours ago
Trypgrep systemd-resolved
orsystemctl status systemd-resolved
.
– telcoM
8 hours ago
@telcoMpgrep systemd-resolved
returns nothing. Doesnameserver 127.0.0.53
really mean the my local machine is running a DNS server?
– Tim
35 mins ago
add a comment |
Yes, the first part indicates that your system is expecting a nameserver to be listening on localhost
, in this case, specifically 127.0.0.53
.
The second part is a search path that is appended to all searches not ending in a period (.
). If you run, for instance, ssh blah
, DNS will first try to look up blah
, then try looking up blah.fios-router.home
.
Thanks. I never know the local machine is running a DNS server. Can you tell me how to find out its process?
– Tim
9 hours ago
Trypgrep systemd-resolved
orsystemctl status systemd-resolved
.
– telcoM
8 hours ago
@telcoMpgrep systemd-resolved
returns nothing. Doesnameserver 127.0.0.53
really mean the my local machine is running a DNS server?
– Tim
35 mins ago
add a comment |
Yes, the first part indicates that your system is expecting a nameserver to be listening on localhost
, in this case, specifically 127.0.0.53
.
The second part is a search path that is appended to all searches not ending in a period (.
). If you run, for instance, ssh blah
, DNS will first try to look up blah
, then try looking up blah.fios-router.home
.
Yes, the first part indicates that your system is expecting a nameserver to be listening on localhost
, in this case, specifically 127.0.0.53
.
The second part is a search path that is appended to all searches not ending in a period (.
). If you run, for instance, ssh blah
, DNS will first try to look up blah
, then try looking up blah.fios-router.home
.
edited 8 hours ago
Jeff Schaller
41.3k1056131
41.3k1056131
answered 9 hours ago
Doug O'NealDoug O'Neal
2,9301818
2,9301818
Thanks. I never know the local machine is running a DNS server. Can you tell me how to find out its process?
– Tim
9 hours ago
Trypgrep systemd-resolved
orsystemctl status systemd-resolved
.
– telcoM
8 hours ago
@telcoMpgrep systemd-resolved
returns nothing. Doesnameserver 127.0.0.53
really mean the my local machine is running a DNS server?
– Tim
35 mins ago
add a comment |
Thanks. I never know the local machine is running a DNS server. Can you tell me how to find out its process?
– Tim
9 hours ago
Trypgrep systemd-resolved
orsystemctl status systemd-resolved
.
– telcoM
8 hours ago
@telcoMpgrep systemd-resolved
returns nothing. Doesnameserver 127.0.0.53
really mean the my local machine is running a DNS server?
– Tim
35 mins ago
Thanks. I never know the local machine is running a DNS server. Can you tell me how to find out its process?
– Tim
9 hours ago
Thanks. I never know the local machine is running a DNS server. Can you tell me how to find out its process?
– Tim
9 hours ago
Try
pgrep systemd-resolved
or systemctl status systemd-resolved
.– telcoM
8 hours ago
Try
pgrep systemd-resolved
or systemctl status systemd-resolved
.– telcoM
8 hours ago
@telcoM
pgrep systemd-resolved
returns nothing. Does nameserver 127.0.0.53
really mean the my local machine is running a DNS server?– Tim
35 mins ago
@telcoM
pgrep systemd-resolved
returns nothing. Does nameserver 127.0.0.53
really mean the my local machine is running a DNS server?– Tim
35 mins ago
add a comment |
The search fios-router.home
part is the last resolvable domain, i.e. your router (iirc Verizon).
127.0.0.53 is the IP address of the nameserver, so your assumption is correct.
New contributor
Thanks. (1) What is "a resolvable domain" and what is "the last resolvable domain"? (2) Do you mean my local machine is running a DNS server? Which process is the DNS server?
– Tim
9 hours ago
add a comment |
The search fios-router.home
part is the last resolvable domain, i.e. your router (iirc Verizon).
127.0.0.53 is the IP address of the nameserver, so your assumption is correct.
New contributor
Thanks. (1) What is "a resolvable domain" and what is "the last resolvable domain"? (2) Do you mean my local machine is running a DNS server? Which process is the DNS server?
– Tim
9 hours ago
add a comment |
The search fios-router.home
part is the last resolvable domain, i.e. your router (iirc Verizon).
127.0.0.53 is the IP address of the nameserver, so your assumption is correct.
New contributor
The search fios-router.home
part is the last resolvable domain, i.e. your router (iirc Verizon).
127.0.0.53 is the IP address of the nameserver, so your assumption is correct.
New contributor
edited 9 hours ago
New contributor
answered 9 hours ago
Radu ChiroviciRadu Chirovici
215
215
New contributor
New contributor
Thanks. (1) What is "a resolvable domain" and what is "the last resolvable domain"? (2) Do you mean my local machine is running a DNS server? Which process is the DNS server?
– Tim
9 hours ago
add a comment |
Thanks. (1) What is "a resolvable domain" and what is "the last resolvable domain"? (2) Do you mean my local machine is running a DNS server? Which process is the DNS server?
– Tim
9 hours ago
Thanks. (1) What is "a resolvable domain" and what is "the last resolvable domain"? (2) Do you mean my local machine is running a DNS server? Which process is the DNS server?
– Tim
9 hours ago
Thanks. (1) What is "a resolvable domain" and what is "the last resolvable domain"? (2) Do you mean my local machine is running a DNS server? Which process is the DNS server?
– Tim
9 hours ago
add a comment |
/etc/resolve.conf
is the main configuration file for the DNS client, so its presence does not imply that you are running a DNS server.
Its primary purpose is to list the IP addresses of DNS servers, in your case:
nameserver 127.0.0.53
- Entries of type
nameserver
tell the host, which DNS server to use. - An entry of type
domain
(if present) tells the system which domain it is in. This allows to be addressed by its host name. (Addition in response to a comment: The hostname is the computer's name in the network. On many systems, you can see the hostname in the command prompt; if not, you can find it by using the commandhostname
.) - An entry of type
search
(if present) would allow computers from different domains to address each other by their respective host names.
The file is nowadays usually generated by NeteworkManager
(for example, on my system, the file starts with the comment "Generated by NetworkManager") or by systemd-resolved
.
systemd-resolved
is a system service that provides network name resolution to local applications. It implements a caching and validating DNS/DNSSEC stub resolver, as well as an LLMNR and MulticastDNS resolver and responder.
Also according to systemd-resolved's manpage, the address 127.0.0.53
is a "local DNS stub listener". On related Stack Exchange sites, there have been questions about how to change this, since the file is /etc/resolv.conf
is automatically generated. See for example
Wrong nameserver set by resolvconf and NetworkManager (Ubuntu SE).
DNS set to systemd's 127.0.0.53 - how to change permanently? (Ubuntu SE).
1
Thanks. (1) "Entries of type nameserver tell the host, which DNS server to use." 127.0.0.53 is an IP of local machine. How is that not contradictory to "its presence does not imply that you are running a DNS server"? (2) "An entry of type domain (if present) tells the system which domain it is in. This allows to be addressed by its host name." What is the difference and relation between a domain (name) and a host name?
– Tim
9 hours ago
1) it is only visible to your local system, not to any other systems; not even within your home network. So it does not serve any others. 2) A hostname might be short (host1
) or fully-qualified (host1.fios-router.home
). In this example, the domain ofhost1.fios-router.home
would befios-router.home
.
– telcoM
8 hours ago
Sols -al /etc/resolv.conf
andcat /etc/resolv.conf
will inform you which program/service is controlling resolv.conf. If you've messed about with your system then you might have a couple of programs competing for control - I had this before with dnsmasq, bind, and systemd-resolved. In addition @Tim, to what telcoM says about your questions: the DNS server and resolver ("stub resolver") can be different, you can pass DNS requests to 127.0.0.53 which pass them to your router for actual DNS (eg it could handle local hosts but pass requests for remote hosts on for full DNS).
– pbhj
6 hours ago
@pbhj "you can pass DNS requests to 127.0.0.53 which pass them to your router for actual DNS." 127.0.0.53 refers to the local machine itself, so why does it pass DNS request to your router ?
– Tim
36 mins ago
add a comment |
/etc/resolve.conf
is the main configuration file for the DNS client, so its presence does not imply that you are running a DNS server.
Its primary purpose is to list the IP addresses of DNS servers, in your case:
nameserver 127.0.0.53
- Entries of type
nameserver
tell the host, which DNS server to use. - An entry of type
domain
(if present) tells the system which domain it is in. This allows to be addressed by its host name. (Addition in response to a comment: The hostname is the computer's name in the network. On many systems, you can see the hostname in the command prompt; if not, you can find it by using the commandhostname
.) - An entry of type
search
(if present) would allow computers from different domains to address each other by their respective host names.
The file is nowadays usually generated by NeteworkManager
(for example, on my system, the file starts with the comment "Generated by NetworkManager") or by systemd-resolved
.
systemd-resolved
is a system service that provides network name resolution to local applications. It implements a caching and validating DNS/DNSSEC stub resolver, as well as an LLMNR and MulticastDNS resolver and responder.
Also according to systemd-resolved's manpage, the address 127.0.0.53
is a "local DNS stub listener". On related Stack Exchange sites, there have been questions about how to change this, since the file is /etc/resolv.conf
is automatically generated. See for example
Wrong nameserver set by resolvconf and NetworkManager (Ubuntu SE).
DNS set to systemd's 127.0.0.53 - how to change permanently? (Ubuntu SE).
1
Thanks. (1) "Entries of type nameserver tell the host, which DNS server to use." 127.0.0.53 is an IP of local machine. How is that not contradictory to "its presence does not imply that you are running a DNS server"? (2) "An entry of type domain (if present) tells the system which domain it is in. This allows to be addressed by its host name." What is the difference and relation between a domain (name) and a host name?
– Tim
9 hours ago
1) it is only visible to your local system, not to any other systems; not even within your home network. So it does not serve any others. 2) A hostname might be short (host1
) or fully-qualified (host1.fios-router.home
). In this example, the domain ofhost1.fios-router.home
would befios-router.home
.
– telcoM
8 hours ago
Sols -al /etc/resolv.conf
andcat /etc/resolv.conf
will inform you which program/service is controlling resolv.conf. If you've messed about with your system then you might have a couple of programs competing for control - I had this before with dnsmasq, bind, and systemd-resolved. In addition @Tim, to what telcoM says about your questions: the DNS server and resolver ("stub resolver") can be different, you can pass DNS requests to 127.0.0.53 which pass them to your router for actual DNS (eg it could handle local hosts but pass requests for remote hosts on for full DNS).
– pbhj
6 hours ago
@pbhj "you can pass DNS requests to 127.0.0.53 which pass them to your router for actual DNS." 127.0.0.53 refers to the local machine itself, so why does it pass DNS request to your router ?
– Tim
36 mins ago
add a comment |
/etc/resolve.conf
is the main configuration file for the DNS client, so its presence does not imply that you are running a DNS server.
Its primary purpose is to list the IP addresses of DNS servers, in your case:
nameserver 127.0.0.53
- Entries of type
nameserver
tell the host, which DNS server to use. - An entry of type
domain
(if present) tells the system which domain it is in. This allows to be addressed by its host name. (Addition in response to a comment: The hostname is the computer's name in the network. On many systems, you can see the hostname in the command prompt; if not, you can find it by using the commandhostname
.) - An entry of type
search
(if present) would allow computers from different domains to address each other by their respective host names.
The file is nowadays usually generated by NeteworkManager
(for example, on my system, the file starts with the comment "Generated by NetworkManager") or by systemd-resolved
.
systemd-resolved
is a system service that provides network name resolution to local applications. It implements a caching and validating DNS/DNSSEC stub resolver, as well as an LLMNR and MulticastDNS resolver and responder.
Also according to systemd-resolved's manpage, the address 127.0.0.53
is a "local DNS stub listener". On related Stack Exchange sites, there have been questions about how to change this, since the file is /etc/resolv.conf
is automatically generated. See for example
Wrong nameserver set by resolvconf and NetworkManager (Ubuntu SE).
DNS set to systemd's 127.0.0.53 - how to change permanently? (Ubuntu SE).
/etc/resolve.conf
is the main configuration file for the DNS client, so its presence does not imply that you are running a DNS server.
Its primary purpose is to list the IP addresses of DNS servers, in your case:
nameserver 127.0.0.53
- Entries of type
nameserver
tell the host, which DNS server to use. - An entry of type
domain
(if present) tells the system which domain it is in. This allows to be addressed by its host name. (Addition in response to a comment: The hostname is the computer's name in the network. On many systems, you can see the hostname in the command prompt; if not, you can find it by using the commandhostname
.) - An entry of type
search
(if present) would allow computers from different domains to address each other by their respective host names.
The file is nowadays usually generated by NeteworkManager
(for example, on my system, the file starts with the comment "Generated by NetworkManager") or by systemd-resolved
.
systemd-resolved
is a system service that provides network name resolution to local applications. It implements a caching and validating DNS/DNSSEC stub resolver, as well as an LLMNR and MulticastDNS resolver and responder.
Also according to systemd-resolved's manpage, the address 127.0.0.53
is a "local DNS stub listener". On related Stack Exchange sites, there have been questions about how to change this, since the file is /etc/resolv.conf
is automatically generated. See for example
Wrong nameserver set by resolvconf and NetworkManager (Ubuntu SE).
DNS set to systemd's 127.0.0.53 - how to change permanently? (Ubuntu SE).
edited 7 hours ago
answered 9 hours ago
Christophe StrobbeChristophe Strobbe
2071213
2071213
1
Thanks. (1) "Entries of type nameserver tell the host, which DNS server to use." 127.0.0.53 is an IP of local machine. How is that not contradictory to "its presence does not imply that you are running a DNS server"? (2) "An entry of type domain (if present) tells the system which domain it is in. This allows to be addressed by its host name." What is the difference and relation between a domain (name) and a host name?
– Tim
9 hours ago
1) it is only visible to your local system, not to any other systems; not even within your home network. So it does not serve any others. 2) A hostname might be short (host1
) or fully-qualified (host1.fios-router.home
). In this example, the domain ofhost1.fios-router.home
would befios-router.home
.
– telcoM
8 hours ago
Sols -al /etc/resolv.conf
andcat /etc/resolv.conf
will inform you which program/service is controlling resolv.conf. If you've messed about with your system then you might have a couple of programs competing for control - I had this before with dnsmasq, bind, and systemd-resolved. In addition @Tim, to what telcoM says about your questions: the DNS server and resolver ("stub resolver") can be different, you can pass DNS requests to 127.0.0.53 which pass them to your router for actual DNS (eg it could handle local hosts but pass requests for remote hosts on for full DNS).
– pbhj
6 hours ago
@pbhj "you can pass DNS requests to 127.0.0.53 which pass them to your router for actual DNS." 127.0.0.53 refers to the local machine itself, so why does it pass DNS request to your router ?
– Tim
36 mins ago
add a comment |
1
Thanks. (1) "Entries of type nameserver tell the host, which DNS server to use." 127.0.0.53 is an IP of local machine. How is that not contradictory to "its presence does not imply that you are running a DNS server"? (2) "An entry of type domain (if present) tells the system which domain it is in. This allows to be addressed by its host name." What is the difference and relation between a domain (name) and a host name?
– Tim
9 hours ago
1) it is only visible to your local system, not to any other systems; not even within your home network. So it does not serve any others. 2) A hostname might be short (host1
) or fully-qualified (host1.fios-router.home
). In this example, the domain ofhost1.fios-router.home
would befios-router.home
.
– telcoM
8 hours ago
Sols -al /etc/resolv.conf
andcat /etc/resolv.conf
will inform you which program/service is controlling resolv.conf. If you've messed about with your system then you might have a couple of programs competing for control - I had this before with dnsmasq, bind, and systemd-resolved. In addition @Tim, to what telcoM says about your questions: the DNS server and resolver ("stub resolver") can be different, you can pass DNS requests to 127.0.0.53 which pass them to your router for actual DNS (eg it could handle local hosts but pass requests for remote hosts on for full DNS).
– pbhj
6 hours ago
@pbhj "you can pass DNS requests to 127.0.0.53 which pass them to your router for actual DNS." 127.0.0.53 refers to the local machine itself, so why does it pass DNS request to your router ?
– Tim
36 mins ago
1
1
Thanks. (1) "Entries of type nameserver tell the host, which DNS server to use." 127.0.0.53 is an IP of local machine. How is that not contradictory to "its presence does not imply that you are running a DNS server"? (2) "An entry of type domain (if present) tells the system which domain it is in. This allows to be addressed by its host name." What is the difference and relation between a domain (name) and a host name?
– Tim
9 hours ago
Thanks. (1) "Entries of type nameserver tell the host, which DNS server to use." 127.0.0.53 is an IP of local machine. How is that not contradictory to "its presence does not imply that you are running a DNS server"? (2) "An entry of type domain (if present) tells the system which domain it is in. This allows to be addressed by its host name." What is the difference and relation between a domain (name) and a host name?
– Tim
9 hours ago
1) it is only visible to your local system, not to any other systems; not even within your home network. So it does not serve any others. 2) A hostname might be short (
host1
) or fully-qualified (host1.fios-router.home
). In this example, the domain of host1.fios-router.home
would be fios-router.home
.– telcoM
8 hours ago
1) it is only visible to your local system, not to any other systems; not even within your home network. So it does not serve any others. 2) A hostname might be short (
host1
) or fully-qualified (host1.fios-router.home
). In this example, the domain of host1.fios-router.home
would be fios-router.home
.– telcoM
8 hours ago
So
ls -al /etc/resolv.conf
and cat /etc/resolv.conf
will inform you which program/service is controlling resolv.conf. If you've messed about with your system then you might have a couple of programs competing for control - I had this before with dnsmasq, bind, and systemd-resolved. In addition @Tim, to what telcoM says about your questions: the DNS server and resolver ("stub resolver") can be different, you can pass DNS requests to 127.0.0.53 which pass them to your router for actual DNS (eg it could handle local hosts but pass requests for remote hosts on for full DNS).– pbhj
6 hours ago
So
ls -al /etc/resolv.conf
and cat /etc/resolv.conf
will inform you which program/service is controlling resolv.conf. If you've messed about with your system then you might have a couple of programs competing for control - I had this before with dnsmasq, bind, and systemd-resolved. In addition @Tim, to what telcoM says about your questions: the DNS server and resolver ("stub resolver") can be different, you can pass DNS requests to 127.0.0.53 which pass them to your router for actual DNS (eg it could handle local hosts but pass requests for remote hosts on for full DNS).– pbhj
6 hours ago
@pbhj "you can pass DNS requests to 127.0.0.53 which pass them to your router for actual DNS." 127.0.0.53 refers to the local machine itself, so why does it pass DNS request to your router ?
– Tim
36 mins ago
@pbhj "you can pass DNS requests to 127.0.0.53 which pass them to your router for actual DNS." 127.0.0.53 refers to the local machine itself, so why does it pass DNS request to your router ?
– Tim
36 mins ago
add a comment |
resolv.conf
is part of the standard way to resolve a host name to an IP address. It is part of the resolver library.
There are different ways to resolve your host name:
- files (specifically:
/etc/hosts
) - dns
- NIS, NIS+ or yp
The sequence in which they are used is in /etc/nsswitch.conf
. This normally says
hosts: files dns
which means that the resolver library first looks in /etc/hosts
and, if it cannot find it there, will use DNS.
Now DNS will query a DNS server. Which one is determined by /etc/resolv.conf
. In addition, there are a number of additional parameters that you can use to help the DNS reolution, of which search
(Try this domain first for the host) is probably the most used.
add a comment |
resolv.conf
is part of the standard way to resolve a host name to an IP address. It is part of the resolver library.
There are different ways to resolve your host name:
- files (specifically:
/etc/hosts
) - dns
- NIS, NIS+ or yp
The sequence in which they are used is in /etc/nsswitch.conf
. This normally says
hosts: files dns
which means that the resolver library first looks in /etc/hosts
and, if it cannot find it there, will use DNS.
Now DNS will query a DNS server. Which one is determined by /etc/resolv.conf
. In addition, there are a number of additional parameters that you can use to help the DNS reolution, of which search
(Try this domain first for the host) is probably the most used.
add a comment |
resolv.conf
is part of the standard way to resolve a host name to an IP address. It is part of the resolver library.
There are different ways to resolve your host name:
- files (specifically:
/etc/hosts
) - dns
- NIS, NIS+ or yp
The sequence in which they are used is in /etc/nsswitch.conf
. This normally says
hosts: files dns
which means that the resolver library first looks in /etc/hosts
and, if it cannot find it there, will use DNS.
Now DNS will query a DNS server. Which one is determined by /etc/resolv.conf
. In addition, there are a number of additional parameters that you can use to help the DNS reolution, of which search
(Try this domain first for the host) is probably the most used.
resolv.conf
is part of the standard way to resolve a host name to an IP address. It is part of the resolver library.
There are different ways to resolve your host name:
- files (specifically:
/etc/hosts
) - dns
- NIS, NIS+ or yp
The sequence in which they are used is in /etc/nsswitch.conf
. This normally says
hosts: files dns
which means that the resolver library first looks in /etc/hosts
and, if it cannot find it there, will use DNS.
Now DNS will query a DNS server. Which one is determined by /etc/resolv.conf
. In addition, there are a number of additional parameters that you can use to help the DNS reolution, of which search
(Try this domain first for the host) is probably the most used.
answered 9 hours ago
Ljm DullaartLjm Dullaart
63629
63629
add a comment |
add a comment |
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You can run
netstat -up
as root to see if and who is listening on port 53 of::
or0.0.0.0
or127.0.0.53
.– eckes
5 hours ago
freedesktop.org/software/systemd/man/… you might be in a systemd-resolved manging mode
– 炸鱼薯条德里克
2 hours ago
Just note that the netmask for localhost is
255.0.0.0
, a /8. So127.0.0.53
is also localhost.– Lenne
2 hours ago
@eckes netstat -up shows nothing is listening
– Tim
9 mins ago