EFA Requirements

Review this topic for requirements for host names, NTP, user privileges, DNS configuration, passwordless SSH, and IP addresses.

Host names: Host names must be alphanumeric. Hyphens are the only special characters allowed. No other special characters are allowed by Kubernetes for cluster formation or by the K3s service.
NTP: The server on which EFA is installed must use NTP or be synchronized to the correct time and timezone. Having the correct time and timezone ensures the following:
- Self-signed certificates have valid start and expiration times.
- EFA logs have the correct time stamp.
- The K3s service starts without errors.
You can edit etc/systemd/timesyncd.conf to select NTP servers in the [Time] section of the configuration file. The NTP= option takes a space-separated list of host names or IP addresses. NTP suggests selecting as many servers as is feasible, but at least 3. Select from the pool of publicly available servers or your company's internal NTP servers. For example:
```
[Time]
NTP=0.pool.ntp.org 1.pool.ntp.org 2.pool.ntp.org 3.pool.ntp.org
```
You can use the following commands to access timesyncd.conf and to synchronize your changes.
```
# sudo vim /etc/systemd/timesyncd.conf
# sudo service systemd-timesyncd restart
# systemctl status systemd-timesyncd
# sudo timedatectl set-timezone <your_time_zone>
```
NTP: All devices that EFA manages must use NTP to ensure easy audit trails and logging from EFA.
User privileges: The user who installs EFA must be a root user or have sudoers privileges to ensure components are installed correctly. Installation fails if this requirement is not met.
DNS: To ensure that DNS resolution of Kubernetes functions correctly, DNS configuration on the nodes must be valid or the /etc/resolv.conf file must be empty.
- Ensure that nslookup returns the correct host name based on the IP address. For example, nslookup node1.
- Ensure that the DNS servers listed in the /etc/resolv.conf file can resolve to the addresses of all the nodes. For example, dig <node_hostname> +short should return the correct IP addresses assigned to the hosts.
TPVM: With the 4.0.x release of TPVM, you can configure DNS, NTP, and LDAP as part of deploying TPVM. For more information, see "Guest OS for TPVM" in the Extreme SLX-OS Management Configuration Guide.