DNS

  • We can name an ip address and ping it directly

  • We can set that name here: /etc/hosts

  • We can see the name of the host using:

    hostname
  • Translating hostname to iip address is called as Name Resolution

  • DNS has host & name resolution files for all machines

  • It is stored at /etc/resolv.conf

  • The order of choosing which record to choose between hosts & DNS is saved in: /etc/nsswitch.conf

  • You can add search entry in /etc/resolv.conf so it can smartly detect what you mean:

    ping web

which is, search mycompany.com

Record Types:

  1. A: Records ip to hostname

  2. AAAA: Records ipv6 to hostname

  3. CNAME: Records name to a name

nslookup

  • Used to query hostname from DNS server

  • Only DNS server & no local host files

dig

  • Returns DNS record in more detail

Network Namespace:

  • Create network namespace using

  • ip netns add <name>
  • Viewing namespaces

    ip netns
  • ip netns exec <name> ip link

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