Linux local dns configuration file

Linux local dns configuration file details when we set up dns in linux, usually in/etc/resolv. the conf file is usually set with several nameservers. In fact, the file can be optimized according to the options. The information contained in the www.2cto.com resolv. conf file is read by the parser routine during their first call. This file is readable and contains keyword list values that provide different types of Parser Information. If the file does not exist, name server queries the domain name resolution configuration of the local machine. Nameserver Name server IP address name server should be an Internet address that can be resolved, that is, the dns server address you set. The maximum value should be MAXNS (currently 3, see <resolv. h>) name servers can be listed. Each name server has the nameserver keyword. If multiple name servers are listed, the parser parses them in order. If no name server exists, the local configuration is used by default. If the query fails, the algorithm queries the following name server until all name servers are queried. Domain Local domain name. set the local domain name. The names query in this domain can use a short name relative to the local domain. If the domain is not set, the host name is used to determine the domain search list for host-name lookup. define the domain name search list. The search list is usually a local domain name. By default, it only contains the local domain name. However, you can follow the key sub-item in the search to change the default domain name. If the parser cannot query their points, it will query the settings in each search path until they match. If the queried server is not local, it may be slow and generate some network traffic. If the server in the domain is unavailable, the query times out. The search currently has a limit of 6 domains, with a total of 256 characters. Options the following options allow you to modify certain parsing variables. The syntax is similar to: options xxx ..., among them, xxx can be the following options: debug sets RES_DEBUG in _ res. options. ndots: n sets a threshold for the number of dots which must appear in a name given to res_query (3) before an initial absolute query will be made. the default for n is 1, meaning that if there are any dots in a name, the name will be tried first as an absolute name before any search list elements are Appended to it. the value for this option is silently capped to 15. this paragraph seems to have no brains .... timeout: the timeout time of the n parser when querying the remote name server. The default value is 5 seconds. Attempts: n sets the name server to be abandoned after the name server fails to be queried several times. The default value is 5. Rotate this will cause the server listed in the nameserver to be cyclically selected during the query, so that all the nameservers of the Server Load balancer can be, instead of asking all clients to try the first listed server no-check-names to prohibit the modern BIND from checking the input host name and the invalid character edns0 (since glibc 2.6) in the email) enable dns extension single-request (since glibc 2.10) in RFC 2671Z. since version 2.9 and later, glibc performs parallel query for IPV4 and IPV6, however, some DNS servers cannot handle this situation well and display request timeout. The secondary option prohibits parallel searches of glibc, so that domain and search keywords are mutually exclusive, if both keywords are set, the last setting takes effect. The value of the search keyword in the resolv. conf file can be changed by the LOCALDOMAIN environment variable lock, and the options keyword can be changed by the Environment Variable RES_OPTIONS.