4 ms·

Anatomy of a DNS Lookup – Part II

106 points by zwischenzug 8y ago

zwischenzug 8y ago
Part I is here: https://zwischenzugs.com/2018/06/08/anatomy-of-a-linux-dns-lookup-part-i/ https://zwischenzugs.com/2018/06/08/anatomy-of-a-linux-dns-l...
pmoriarty 8y ago
"The --read-environment flag is undocumented, and is there so that systemctl can play nice with it. A lot of people hate systemctl for this kind of thing." Is such undocumented behavior an intentional, acknowledged policy of systemd? Or is this just something that got overlooked and will/should be documented sometime?
- gcommer 8y ago
  Its not a part of systemd, its a part of ifupdown that was added to aide Debian's transition from SysV to systemd. Seems unfair to me to count this against systemd; there are other less intrusive ways this could've been done, and "allow reading configuration from env vars" is probably a good thing anyways. https://github.com/wido/ifupdown/commit/c29820f370a4905b836660ee4cf0162cdafdac66 https://github.com/wido/ifupdown/commit/c29820f370a4905b8366...
  - riobard 8y ago
    Is there any detailed roadmap of Debian's transition from SysV to systemd? Currently it's a mess in Debian 9 where some packages come with traditional init scripts and some with systemd unit files, and some even with upstart scripts.
  - zwischenzug 8y ago
    Author here. It may be unfair, I didn't mean to imply any kind of judgement. 'This kind of thing' was vague, but was intended to get over the fact that systemd is taking over more and more of the OS, and people don't like this. Whether this is good or bad I'm fairly agnostic on. At least it's managed and a standard.
    - aargh_aargh 8y ago
      I'm not one to flame on systemd but I have to correct you there - it's not a standard, it's a single implementation.
unixbhaskar 8y ago
Cool Ian!
oxymoron 8y ago
If you are curious about the low level details of DNS, you might want to check out an article I wrote about how to build a DNS server from first principles: https://github.com/EmilHernvall/dnsguide https://github.com/EmilHernvall/dnsguide
xmichael999 8y ago
One of the first things I do on any ubuntu box is apt-get purge resolvconf

106 points by zwischenzug 8y ago

Part I is here: https://zwischenzugs.com/2018/06/08/anatomy-of-a-linux-dns-lookup-part-i/ https://zwischenzugs.com/2018/06/08/anatomy-of-a-linux-dns-l...

pmoriarty 8y ago

"The --read-environment flag is undocumented, and is there so that systemctl can play nice with it. A lot of people hate systemctl for this kind of thing." Is such undocumented behavior an intentional, acknowledged policy of systemd? Or is this just something that got overlooked and will/should be documented sometime?

gcommer 8y ago
Its not a part of systemd, its a part of ifupdown that was added to aide Debian's transition from SysV to systemd. Seems unfair to me to count this against systemd; there are other less intrusive ways this could've been done, and "allow reading configuration from env vars" is probably a good thing anyways. https://github.com/wido/ifupdown/commit/c29820f370a4905b836660ee4cf0162cdafdac66 https://github.com/wido/ifupdown/commit/c29820f370a4905b8366...
- riobard 8y ago
  Is there any detailed roadmap of Debian's transition from SysV to systemd? Currently it's a mess in Debian 9 where some packages come with traditional init scripts and some with systemd unit files, and some even with upstart scripts.
- zwischenzug 8y ago
  Author here. It may be unfair, I didn't mean to imply any kind of judgement. 'This kind of thing' was vague, but was intended to get over the fact that systemd is taking over more and more of the OS, and people don't like this. Whether this is good or bad I'm fairly agnostic on. At least it's managed and a standard.
  - aargh_aargh 8y ago
    I'm not one to flame on systemd but I have to correct you there - it's not a standard, it's a single implementation.

unixbhaskar 8y ago

Cool Ian!

oxymoron 8y ago

If you are curious about the low level details of DNS, you might want to check out an article I wrote about how to build a DNS server from first principles: https://github.com/EmilHernvall/dnsguide https://github.com/EmilHernvall/dnsguide

xmichael999 8y ago

One of the first things I do on any ubuntu box is apt-get purge resolvconf