Re: Where is /etc/resolv.conf defined?
Joel Hammer wrote: Thanks. I have no idea about kernels and libraries, all just mystical C talk to me. I was asking this question because I wanted to understand if I had to rename my /etc/resolv.conf.dhcp file to /etc/resolv.conf after dhcpcd creates the latter file. I guess the answer would be yes, if I want to be sure I am using the current name servers. Since I use a caching name server, I don't think that i crucial. Joel A symlink should work well, too. That way dhcpcd always has its copy of the file as it expects, and apps that use resolv.conf have the latest version, too. Dave ___ Linux-users mailing list Archives, Digests, etc at http://linux.nf/mailman/listinfo/linux-users
Re: Where is /etc/resolv.conf defined?
Kurt Wall wrote: [...] glibc -- particularly, the resolver library and the NSS (Name Service Switch) facilities. Specifically, the file resolv/resolv.h defines the macro _PATH_RESCONF: #define _PATH_RESCONF /etc/resolv.conf Here's a question that came up in our study group. Do name lookups (name to IP mappings) get cached on a client machine (one without a nameserver)? Arp lookups (MAC to IP mappings) do, but what about DNS? My answer was that they don't. My reasoning was that name resolution is handled by glibc, so it's running in user space, so the results aren't available to other applications. I guess you could say that an application may cache the lookup, but if 2 applications use the same name there are 2 lookups done. Naturally this is easy to answer empirically, but I don't have all the network tools I'd like at the moment. Thanks! Dave ___ Linux-users mailing list Archives, Digests, etc at http://linux.nf/mailman/listinfo/linux-users
Re: Where is /etc/resolv.conf defined?
Scribbling feverishly on January 10, Dave Anselmi managed to emit: Kurt Wall wrote: [...] glibc -- particularly, the resolver library and the NSS (Name Service Switch) facilities. Specifically, the file resolv/resolv.h defines the macro _PATH_RESCONF: #define _PATH_RESCONF /etc/resolv.conf Here's a question that came up in our study group. Do name lookups (name to IP mappings) get cached on a client machine (one without a nameserver)? Arp lookups (MAC to IP mappings) do, but what about DNS? I suppose this is an implementation detail, but RFC1035 suggests that resolver libraries should cache all data: 7.4. Using the cache In general, we expect a resolver to cache all data which it receives in responses since it may be useful in answering future client requests. However, there are several types of data which should not be cached: - When several RRs of the same type are available for a particular owner name, the resolver should either cache them all or none at all. When a response is truncated, and a resolver doesn't know whether it has a complete set, it should not cache a possibly partial set of RRs. - Cached data should never be used in preference to authoritative data, so if caching would cause this to happen the data should not be cached. - The results of an inverse query should not be cached. ... In a similar vein, when a resolver has a set of RRs for some name in a response, and wants to cache the RRs, it should check its cache for already existing RRs. Depending on the circumstances, either the data in the response or the cache is preferred, but the two should never be combined. If the data in the response is from authoritative data in the answer section, it is always preferred. Kurt -- You will gain money by an immoral action. ___ Linux-users mailing list Archives, Digests, etc at http://linux.nf/mailman/listinfo/linux-users
Re: Where is /etc/resolv.conf defined?
Scribbling feverishly on January 09, Joel Hammer managed to emit: I would like to know how my linux box knows that /etc/resolv.conf is the place to look for dns servers. I have grepped through the linux sources, but could not find any file with resolv.conf in it. glibc -- particularly, the resolver library and the NSS (Name Service Switch) facilities. Specifically, the file resolv/resolv.h defines the macro _PATH_RESCONF: #define _PATH_RESCONF /etc/resolv.conf I grepped /etc and found a few files. One is /etc/lst.cnf, which has all the various files defined, like so: FILE_ETC_HOSTS=/etc/hosts FILE_ETC_RESOLV_CONF=/etc/resolv.conf FILE_ETC_NETWORKS=/etc/networks FILE_ETC_EXPORTS=/etc/exports FILE_ETC_GATEWAYS=/etc/gateways FILE_ETC_HOST_CONF=/etc/host.conf FILE_ETC_INETD_CONF=/etc/inetd.conf FILE_ETC_RC_INET1=$DIR_INIT_CONF/rc.inet1 FILE_ETC_RC_INET2=$DIR_INIT_CONF/rc.inet2 Is this file the basic source file that defines where all these basic files should be? Which programs actually use this file, lst.cnf? No. lst.cnf is the configuration file that used to be used by Caldera's lisa tool. It may still be used by some of Caldera's newer configuration and installation tools, but I no longer track Caldera, so I can't be certain. Kurt -- Be cautious in your daily affairs. ___ Linux-users mailing list Archives, Digests, etc at http://linux.nf/mailman/listinfo/linux-users
Re: Where is /etc/resolv.conf defined?
Thanks. I have no idea about kernels and libraries, all just mystical C talk to me. I was asking this question because I wanted to understand if I had to rename my /etc/resolv.conf.dhcp file to /etc/resolv.conf after dhcpcd creates the latter file. I guess the answer would be yes, if I want to be sure I am using the current name servers. Since I use a caching name server, I don't think that i crucial. Joel ___ Linux-users mailing list Archives, Digests, etc at http://linux.nf/mailman/listinfo/linux-users
RE: Where is /etc/resolv.conf defined?
Well Kurt it is still be used by Caldera I'm running OpenServer 3.1 here Regards Lavinius Romio Petru www.rom-tech.net [EMAIL PROTECTED] -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] On Behalf Of Kurt Wall Sent: Thursday, 10 January 2002 12:03 PM To: [EMAIL PROTECTED] Subject: Re: Where is /etc/resolv.conf defined? Scribbling feverishly on January 09, Joel Hammer managed to emit: I would like to know how my linux box knows that /etc/resolv.conf is the place to look for dns servers. I have grepped through the linux sources, but could not find any file with resolv.conf in it. glibc -- particularly, the resolver library and the NSS (Name Service Switch) facilities. Specifically, the file resolv/resolv.h defines the macro _PATH_RESCONF: #define _PATH_RESCONF /etc/resolv.conf I grepped /etc and found a few files. One is /etc/lst.cnf, which has all the various files defined, like so: FILE_ETC_HOSTS=/etc/hosts FILE_ETC_RESOLV_CONF=/etc/resolv.conf FILE_ETC_NETWORKS=/etc/networks FILE_ETC_EXPORTS=/etc/exports FILE_ETC_GATEWAYS=/etc/gateways FILE_ETC_HOST_CONF=/etc/host.conf FILE_ETC_INETD_CONF=/etc/inetd.conf FILE_ETC_RC_INET1=$DIR_INIT_CONF/rc.inet1 FILE_ETC_RC_INET2=$DIR_INIT_CONF/rc.inet2 Is this file the basic source file that defines where all these basic files should be? Which programs actually use this file, lst.cnf? No. lst.cnf is the configuration file that used to be used by Caldera's lisa tool. It may still be used by some of Caldera's newer configuration and installation tools, but I no longer track Caldera, so I can't be certain. Kurt -- Be cautious in your daily affairs. smime.p7s Description: application/pkcs7-signature
