Learn how to modify the DNS and default gateway configuration of a TCP/IP stack on a host. You can also change the congestion control algorithm, the maximum number of connections, and the name of custom TCP/IP stacks.

Note: You can change the DNS and default gateway configuration of the default TCP/IP stack only. Multiple DNS and gateways configurations are supported when using separate TCP/IP stacks.

Procedure

  1. In the vSphere Client, navigate to the host.
  2. On the Configure tab, expand Networking and select TCP/IP configuration.
  3. Select a stack from the table, click Edit and make the appropriate changes.
    Page Option
    DNS Configuration Select a method of obtaining the DNS server.
    • Select Obtain settings automatically from a VMkernel network adapter and select a network adapter from the VMKernel network adapter drop-down menu
    • Select Enter settings manually and edit the DNS configuration settings.
      1. Edit the Host name.
      2. Edit the Domain name.
      3. Type a preferred DNS server IP address.
      4. Type an alternate DNS server IP address.
      5. (Optional) Use the Search domains text box to specify DNS suffixes to use in DNS search when resolving unqualified domain names.
    Routing Edit the VMkernel gateway information.
    Note: Removing the default gateway might cause the client to lose connectivity with the host.
    Name Change the name of a custom TCP/IP stack
    Advanced Edit the maximum number of connections and the congestion control algorithm of the stack
  4. Click OK to apply your changes.

What to do next

You can add static routes to additional gateways by using CLI commands. For more information, see http://kb.vmware.com/kb/2001426

Explicit Congestion Notification

Explicit Congestion Notification (ECN) allows a TCP sender to reduce the transmission rate to avoid packet drops. ECN is specified in RFC 3168. vSphere 7.0 and later supports ECN and it is enabled by default.

You can get the ECN status of any netstack using esxcli command.

Procedure

  1. In the ESXi Shell on the host, use the following command.
    esxcli network ip netstack set -N <NetStack-Name> --ecn=<str>
  2. You can set the status of ECN. The setting has the following possible values in ESXi. 
    ...
  --ecn=<str>           The status of ECN (Explicit Congestion Notification).
                            disabled: Completely disable ECN functionality
                            echo-only: Only echoing ECN, won't initiate
                            enabled: Fully enable ECN functionality
    The default value of this parameter is enabled. ESXi is likely to use ECN if the value of this parameter is enabled. If a router or a network appliance in the environment cannot handle IP packets with ECN bits accurately, then the ECN capability can be set to disabled.