Red Hat RHCSARHCE 7 Cert Guide（六）

zhangleivod

1.Private network addresses are addresses that are for use in internal networks only.
        10.0.0.0/8 ( a single Class A network)(10.0.0.0-10.255.255.255)
        172.16.0.0/12 (16 Class B networks)(172.16.0.0-172.31.255.255)
        192.168.0.0/16 (256 Class C networks)(192.168.0.0-192.168.255.255)
2.this private IP address is replaced with the IP address of the NAT router. Hence, nodes on the
        Internet think that they are communicating with the NAT router, and not with the
        individual hosts.
3.IPv6 :Multiple sequences of 0000 can be written as ::
4.CIDR(classless interdomain routing):192.168.10.100/24
        192.168.10.100/24, the broadcast address is 192.168.10.255
        Transfer Control Protocol(TCP)
        User Datagram Protocol (UDP)
        Dynamic Host Configuration Protocol (DHCP)
        Internet Control Message Protocol (ICMP)
        Ethernet interfaces begin with en, WLAN interfaces begin with wl, and WWAN interfaces begin with ww
        Based on this information, device names such as eno16777734 can be used
5.
        ip addr to configure and monitor network addresses
        ip route to configure and monitor routing information
        ip link to configure and monitor network link state
6.To show current network settings, you can use the ip addr show command (which can be abbreviated as ip a s or even as ip a ).
        ip addr show
        ip link show       
        ip link set dev eno16777736 up
        ip -s link : This shows all existing network connections, in addition to statistics about the number of packets that have been sent and associated error messages.
7.To verify availability of ports on your server, you can use the netstat command, or the newer ss command, which provides the same functionality.
        ss -tunlp |grep 8001
        netstat -anp |grep LISTEN |grep 8001
        ping -c 4 8.8.8.8
        ip addr add 10.0.0.10/24 dev eno16777736
8.systemctl status NetworkManager
        (When NetworkManager comes up, it reads the network card configuration scripts, which are in /etc/sysconfig/network-scripts and
        have a name that starts with ifcfg and is followed by the name of the network card.)
        nmtui (nmgui)
        on the RHCSA exam, it is perfectly fine to use the nmtui text user interface command;
9.
        nmcli con show
        nmcli con show eno16777736
        man 5 nm-settings: To find out what exactly these settings are doing, read man 5 nm-settings
        nmcli dev status
        nmcli dev show eno16777736
        man nmcli-examples
        nm-connection-editor
        Every connection that you create is stored as a configuration file in the directory /etc/sysconfig/network-scripts.
        nmcli con reload:After making changes to the configuration file, use the nmcli con reload command to activate the new configuration.

       
10.hostnamectl set-hostname + name (vi /etc/hostname)
        hostnamectl set-hostname myhost.example.com
        hostnamectl status
        /etc/hosts(DNS)
        If a host has more than one name, like a short name and a fully qualified DNS name,
        you can specify both of them in /etc/hosts. In that case, the second column must
        contain the FQDN, and the third column can contain the alias.
        /etc/resolv.conf file, which is used for DNS name server resolving.
11.Do not specify the DNS servers directly in /etc/resolv.conf. They will be overwritten by NetworkManager .