Skip to main content
Unix & Linux

Return to Answer

added 253 characters in body
Source Link
user313992
user313992

To answer just your last question: /etc/hosts doesn't apply again immediately because firefox is caching the last hostname it got for google.com; if you want it to always fetch it again, you'll have to set network.dnsCacheExpiration to 0 in about:config. More info (though a bit outdated) here. Sorry if this is offtopic.

As a sidenote, many programs don't use the standard resolver (getaddrinfo(3), getnameinfo(3) [1]) because it sucks.

First, the interface is not asynchronous; any moderately complex program will have to spawn a separate thread doing just the getaddrinfo() and then invent its own protocol to communicate with it (and let's not even enter into getaddrinfo_a(), which is sending a signal upon completion, so it's even worse).

Second, the resolver implementation in glibc (the standard C library in linux) is horrible, expecting you to let it pull random dynamic objects into the address space via dlopen() behind your back, and making it impossible to contain it in any way or use it in statically linked executables.

Since many programs don't use the standard resolver directly, they also don't bother to replicate its behavior exactly, and ignore some or all of /etc/resolv.conf, /etc/hosts, /etc/nsswitch.conf or /etc/gai.conf.

[1] and don't even mention the non-reentrant, ipv4-only gethostbyname(), which was deprecated since ages.

To answer just your last question: /etc/hosts doesn't apply again immediately because firefox is caching the last hostname it got for google.com; if you want it to always fetch it again, you'll have to set network.dnsCacheExpiration to 0 in about:config. More info (though a bit outdated) here. Sorry if this is offtopic.

As a sidenote, many programs don't use the standard resolver (getaddrinfo(3), getnameinfo(3) [1]) because it sucks.

First, the interface is not asynchronous; any moderately complex program will have to spawn a separate thread doing just the getaddrinfo() and then invent its own protocol to communicate with it (and let's not even enter into getaddrinfo_a(), which is sending a signal upon completion, so it's even worse).

Second, the resolver implementation in glibc (the standard C library in linux) is horrible, expecting you to let it pull random dynamic objects into the address space via dlopen() behind your back, and making it impossible to contain it in any way or use it in statically linked executables.

[1] and don't even mention gethostbyname(), which was deprecated since ages.

To answer just your last question: /etc/hosts doesn't apply again immediately because firefox is caching the last hostname it got for google.com; if you want it to always fetch it again, you'll have to set network.dnsCacheExpiration to 0 in about:config. More info (though a bit outdated) here. Sorry if this is offtopic.

As a sidenote, many programs don't use the standard resolver (getaddrinfo(3), getnameinfo(3) [1]) because it sucks.

First, the interface is not asynchronous; any moderately complex program will have to spawn a separate thread doing just the getaddrinfo() and then invent its own protocol to communicate with it (and let's not even enter into getaddrinfo_a(), which is sending a signal upon completion, so it's even worse).

Second, the resolver implementation in glibc (the standard C library in linux) is horrible, expecting you to let it pull random dynamic objects into the address space via dlopen() behind your back, and making it impossible to contain it in any way or use it in statically linked executables.

Since many programs don't use the standard resolver directly, they also don't bother to replicate its behavior exactly, and ignore some or all of /etc/resolv.conf, /etc/hosts, /etc/nsswitch.conf or /etc/gai.conf.

[1] and don't even mention the non-reentrant, ipv4-only gethostbyname(), which was deprecated since ages.

added 2 characters in body
Source Link
user313992
user313992

To answer just your last question: /etc/hosts doesn't apply again immediately because firefox is caching the last hostname it got for google.com; if you want it to always fetch it again, you'll have to set network.dnsCacheExpirationnetwork.dnsCacheExpiration to 0 in about:config. More info (though a bit outdated) here. Sorry if this is offtopic.

As a sidenote, many programs don't use the standard resolver (getaddrinfo(3), getnameinfo(3) [1]) because it sucks.

First, the interface is not asynchronous; any moderately complex program will have to spawn a separate thread doing just the getaddrinfo() and then invent its own protocol to communicate with it (and let's not even enter into getaddrinfo_a(), which is sending a signal upon completion, so it's even worse).

Second, the resolver implementation in glibc (the standard C library in linux) is horrible, expecting you to let it pull random dynamic objects into the address space via dlopen() behind your back, and making it impossible to contain it in any way or use it in statically linked executables.

[1] and don't even mention gethostbyname(), which was deprecated since ages.

To answer just your last question: /etc/hosts doesn't apply again immediately because firefox is caching the last hostname it got for google.com; if you want it to always fetch it again, you'll have to set network.dnsCacheExpiration to 0 in about:config. More info (though a bit outdated) here. Sorry if this is offtopic.

As a sidenote, many programs don't use the standard resolver (getaddrinfo(3), getnameinfo(3) [1]) because it sucks.

First, the interface is not asynchronous; any moderately complex program will have to spawn a separate thread doing just the getaddrinfo() and then invent its own protocol to communicate with it (and let's not even enter into getaddrinfo_a(), which is sending a signal upon completion, so it's even worse).

Second, the resolver implementation in glibc (the standard C library in linux) is horrible, expecting you to let it pull random dynamic objects into the address space via dlopen() behind your back, and making it impossible to contain it in any way or use it in statically linked executables.

[1] and don't even mention gethostbyname(), which was deprecated since ages.

To answer just your last question: /etc/hosts doesn't apply again immediately because firefox is caching the last hostname it got for google.com; if you want it to always fetch it again, you'll have to set network.dnsCacheExpiration to 0 in about:config. More info (though a bit outdated) here. Sorry if this is offtopic.

As a sidenote, many programs don't use the standard resolver (getaddrinfo(3), getnameinfo(3) [1]) because it sucks.

First, the interface is not asynchronous; any moderately complex program will have to spawn a separate thread doing just the getaddrinfo() and then invent its own protocol to communicate with it (and let's not even enter into getaddrinfo_a(), which is sending a signal upon completion, so it's even worse).

Second, the resolver implementation in glibc (the standard C library in linux) is horrible, expecting you to let it pull random dynamic objects into the address space via dlopen() behind your back, and making it impossible to contain it in any way or use it in statically linked executables.

[1] and don't even mention gethostbyname(), which was deprecated since ages.

Source Link
user313992
user313992

To answer just your last question: /etc/hosts doesn't apply again immediately because firefox is caching the last hostname it got for google.com; if you want it to always fetch it again, you'll have to set network.dnsCacheExpiration to 0 in about:config. More info (though a bit outdated) here. Sorry if this is offtopic.

As a sidenote, many programs don't use the standard resolver (getaddrinfo(3), getnameinfo(3) [1]) because it sucks.

First, the interface is not asynchronous; any moderately complex program will have to spawn a separate thread doing just the getaddrinfo() and then invent its own protocol to communicate with it (and let's not even enter into getaddrinfo_a(), which is sending a signal upon completion, so it's even worse).

Second, the resolver implementation in glibc (the standard C library in linux) is horrible, expecting you to let it pull random dynamic objects into the address space via dlopen() behind your back, and making it impossible to contain it in any way or use it in statically linked executables.

[1] and don't even mention gethostbyname(), which was deprecated since ages.