Resolvconf
Encyclopedia
In some Linux
distributions and related computer
operating system
s, the resolvconf program maintains the system information about the currently available nameservers and manages the contents of the configuration file
resolv.conf
, which determines Domain Name System
(DNS) resolver parameters.
Before a computer can connect to an external network resource by name (e.g., www.google.com), it must have a means of converting the alpha-numeric names (e.g., wikipedia.org) into numeric network addresses (e.g., 66.230.200.10). The Internet uses these numeric IP address
es as network addresses.
The configuration file resolv.conf normally contains information about the nameservers to be used by the system. However, when multiple programs need to dynamically modify the resolv.conf file they can interfere with each other and the file status can be invalid. The resolvconf program addresses this problem. It acts as an intermediary between programs that supply nameserver information (e.g., DHCP clients) and programs that use nameserver information (e.g., resolver).
When resolvconf is properly installed, the resolv.conf file at is replaced by a symbolic link
to /etc/resolvconf/run/resolv.conf and the resolver instead uses the dynamically generated linked file.
The resolvconf program is only necessary when a system has multiple programs that need to dynamically modify the nameserver information. In a simple system where the nameservers do not change often or are only changed by one program, the resolv.conf configuration file is adequate.
Linux
Linux is a Unix-like computer operating system assembled under the model of free and open source software development and distribution. The defining component of any Linux system is the Linux kernel, an operating system kernel first released October 5, 1991 by Linus Torvalds...
distributions and related computer
Computer
A computer is a programmable machine designed to sequentially and automatically carry out a sequence of arithmetic or logical operations. The particular sequence of operations can be changed readily, allowing the computer to solve more than one kind of problem...
operating system
Operating system
An operating system is a set of programs that manage computer hardware resources and provide common services for application software. The operating system is the most important type of system software in a computer system...
s, the resolvconf program maintains the system information about the currently available nameservers and manages the contents of the configuration file
Configuration file
In computing, configuration files, or config files configure the initial settings for some computer programs. They are used for user applications, server processes and operating system settings. The files are often written in ASCII and line-oriented, with lines terminated by a newline or carriage...
resolv.conf
Resolv.conf
resolv.conf is the name of a computer file used in various operating systems to configure the Domain Name System resolver library. The file is a plain-text file usually created by the network administrator or by applications that manage the configuration tasks of the system...
, which determines Domain Name System
Domain name system
The Domain Name System is a hierarchical distributed naming system for computers, services, or any resource connected to the Internet or a private network. It associates various information with domain names assigned to each of the participating entities...
(DNS) resolver parameters.
Before a computer can connect to an external network resource by name (e.g., www.google.com), it must have a means of converting the alpha-numeric names (e.g., wikipedia.org) into numeric network addresses (e.g., 66.230.200.10). The Internet uses these numeric IP address
IP address
An Internet Protocol address is a numerical label assigned to each device participating in a computer network that uses the Internet Protocol for communication. An IP address serves two principal functions: host or network interface identification and location addressing...
es as network addresses.
The configuration file resolv.conf normally contains information about the nameservers to be used by the system. However, when multiple programs need to dynamically modify the resolv.conf file they can interfere with each other and the file status can be invalid. The resolvconf program addresses this problem. It acts as an intermediary between programs that supply nameserver information (e.g., DHCP clients) and programs that use nameserver information (e.g., resolver).
When resolvconf is properly installed, the resolv.conf file at is replaced by a symbolic link
Symbolic link
In computing, a symbolic link is a special type of file that contains a reference to another file or directory in the form of an absolute or relative path and that affects pathname resolution. Symbolic links were already present by 1978 in mini-computer operating systems from DEC and Data...
to /etc/resolvconf/run/resolv.conf and the resolver instead uses the dynamically generated linked file.
The resolvconf program is only necessary when a system has multiple programs that need to dynamically modify the nameserver information. In a simple system where the nameservers do not change often or are only changed by one program, the resolv.conf configuration file is adequate.
External links
- resolvconf. Original implementation.
- openresolv. Compatible implementation.
- man page. resolvconf.
- docs.sun.com. Solaris 2.7 "resolv.conf" man page.