Networking Flashcards
What are the fundamental physical components of a LAN?
three major components:
server/computers; devices like nic, switches, gateway or routers; transmission media – wired or
wireless, ethernet, optic fibre, coaxial cable.
Which command-line tool is utilized for managing network connections in Linux-based
operating systems?
nmcli – network manager command line interface
What command is used to retrieve the public IP address?
curl ifconfig.me public ip is the
ip assigned by the internet service provider.
How can the profiles of network interfaces be listed using the nmcli command?
nmcli
connection show
Which command is used to list the network interfaces?
ifconfig, nmcli dev show, ipaddr or ip as
What is the command employed to create a new connection profile?
nmcli connection add
What command is used to modify a connection profile?
nmcli connection modify
What command is used to delete a connection profile?
nmcli connection delete
How would you determine which interface is responsible for sending and receiving traffic
outside the network?
route -n
What does the term "IP address" signify?
internet protocol address, a logical number that is assigned to the NIC of a host so that the host can be uniquely identified over the TCP/IP network.
What is the function of a gateway?
a device that helps you to take the traffic out and bring it in,
a gate between the networks.
What is the purpose of a DNS server?
domain name service maps the hostname to ip address
and ip address to hostname.
What constitutes a DHCP server?
dynamic host configuration protocol – a server which assigns
the ip address automatiocally, port number 67 for dhcp server, dhcp client port number 68.
DORA process: how the ip address is assigned – Discover Offer Request Accept
What does NAT service refer to?
a service in the router – network address translation –
responsible for mapping private ip into public ip and vice versa.
What is dynamic routing protocol?
a protocol inside the router that is responsible for writing the dynamic routing table (where to send and receive packets)
For what purpose is the ping command used, and which protocol does it utilize?
it checks the
connectivity of the remote server, used to get the latency in the network (how much time
packets take to reach destination), visibility of server on network. It uses ICMP.
Which TCP/IP setting (directives) is necessary for a workstation to function?
ipaddr, netmask,
gateway, bootproto, onboot – what you add in network configuration file for static ip.
Define "Subnet Mask"
divides the ip address into two separate portions – host (0) and network
Which IP address remains constant?
loopback address – 127.0.0.1
How can the IP address of a remote hostname be obtained?
nslookup <hostname>
What do you mean by “forward lookup”?
mapping the hostname into ip address – nslookup
<hostname>
- What does "reverse lookup" indicate?
mapping the ip address into hostname – nslookup <ip
address>
What is the significance of a loopback address?
checks the connectivity of the TCP stack.
Which configuration file contains networking interface configuration for Redhat/CentOS/OEL 7?
/etc/sysconfig/network-scripts/ifcfg-<interface name>
Which command is used to display the routing table?
netstat -rn and/or route -n
What is DNS client configuration file?
/etc/resolv.conf
What purpose does the /etc/hosts file serve?
/etc/hosts is a stub resolver which maps the hostname into ip address.
Which file specifies the sequence and methods for utilizing naming and service resolution
services?
/etc/nsswitch.conf
Differentiate between a switch and a router.
switch – connects devices within a network,
datalink layer, frames. Router – connects two networks, manages the packets, network layer
What is the file path for storing networking configuration (interface configuration)?
/etc/sysconfig/network-scripts/ifcfg-<interface name>
How would you identify if a port is listening to or not on a local server?
netstat -tunap | grep -i
listen or ss -tunap | grep -i listen or lsof -i :<port number>
How would you identify if a port is listening to or not on a remote server?
nmap <remote
server ip address> <port number> or telnet <remote server ip> <port number> will show escape
character
What method can be used to verify if a server's cable is connected?
ethtool <interface name>
will state link detected.
In RHEL 6 & 7, what is the host-based firewall known as?
iptables in RHEL 6
firewalld in RHEL 7
Define NIC and explain how NICs can be listed.
a device – with an ip address - which
sends and receives packets within and outside the network.
If you can successfully ping within your network but not outside of it, what steps would you take for troubleshooting?
check if the gateway is assigned with route -n, UG means
up gateway.
What troubleshooting steps would you follow if you are unable to ping the internet?
a. check if cable is connected with ethtool <interface name>.
b. Check systemctl status NetworkManager/network (whether service is working or not).
c. nmcli connection show to see if connection is up.
What are the steps you would take for network troubleshooting?
a. Check the cable with ethtool.
b. Check the service with systemctl status network.
c. Check connection with nmcli connection show.
d. Check configuration file.
e. Check routing table if gateway is assigned with route -n.
f. Check if DNS is present in /etc/resolv.conf
