# Computer Networks/Network Services

This lesson introduces network services.

## Objectives and Skills

Objectives and skills for the network services portion of Network+ certification include:
* Install and configure the following networking services/applications
** DHCP
*** Static vs dynamic IP addressing
*** Reservations
*** Scopes
*** Leases
*** Options (DNS servers, suffixes)
*** IP helper/DHCP relay
** DNS
*** DNS servers
*** DNS records (A, MX, AAAA, CNAME, PTR)
*** Dynamic DNS
** Proxy/reverse proxy
** NAT
*** PAT
*** SNAT
*** DNAT
** Port forwarding
* Compare and contrast the following ports and protocols
** 80 HTTP
** 443 HTTPS
** 137-139 NetBIOS
** 110 POP
** 143 IMAP
** 25 SMTP
** 5060/5061 SIP
** 2427/2727 MGCP
** 5004/5005 RTP
** 1720 H.323
** TCP
*** Connection-oriented
** UDP
*** Connectionless
* Given a scenario, configure and apply the appropriate ports and protocols
** 20,21 FTP
** 161 SNMP
** 22 SSH
** 23 Telnet
** 53 DNS
** 67,68 DHCP
** 69 TFTP
** 445 SMB
** 3389 RDP

## Readings

* Wikipedia: Dynamic Host Configuration Protocol
* Wikipedia: Domain Name System
* Wikipedia: Proxy server
* Wikipedia: Network address translation
* Wikipedia: Port forwarding

## Multimedia

* YouTube: DHCP Addressing Overview - CompTIA Network+ N10-006 - 1.3
* YouTube: DHCP Reservations - CompTIA Network+ N10-006 - 1.3
* YouTube: DHCP Scopes - CompTIA Network+ N10-006 - 1.3
* YouTube: DHCP Leases - CompTIA Network+ N10-006 - 1.3
* YouTube: DHCP Options - CompTIA Network+ N10-006 - 1.3
* YouTube: An Overview of DNS - CompTIA Network+ N10-006 - 1.3
* YouTube: DNS Records - CompTIA Network+ N10-006 - 1.3
* YouTube: Dynamic DNS - CompTIA Network+ N10-006 - 1.3
* YouTube: Proxy Servers - CompTIA Network+ N10-006 - 1.3
* YouTube: Understanding Network Address Translation - CompTIA Network+ N10-006 - 1.3
* YouTube: Common TCP and UDP Ports - CompTIA Network+ N10-006 - 5.9
* YouTube: Application Ports and Protocols - CompTIA Network+ N10-006 - 5.10

## Activities

* Review Wikipedia: ipconfig. Use the ipconfig command to view, renew, release, and obtain an IP address through DHCP.
* Review Wikipedia: nslookup. Use the following commands to display and query DNS information.
** Use ipconfig /all to display DNS server information.
** Use nslookup to display host addresses.
** Use nslookup to display other record types.
** Use nslookup to simulate a recursive query.
* Compare private and public IP addresses.
** Review Wikipedia: Private network.
** Use ipconfig to display your IP address. Compare your address to the private network address spaces. Is your local IP address a private or public IP address?
** Perform an Internet search for "What's my IP". Use the returned information or one of the available sites to identify your public IP address. If this address is different, determine what device is providing NAT services for your network.
** Use the tracert command to trace the route from your computer to Google's DNS server at 8.8.8.8. Can you find the NAT device in the trace?
* Review Wikipedia: netstat. Use the netstat command to display network connections and statistics.
** Use netstat to Display Active TCP Connections
** Use netstat -a -n to Display All Active Connections (TCP and UDP)
** Use netstat -s to Display Statistics by Protocol
** Use ARIN.net:WhoisRWS or your local regional Internet registry to look up host information for any IP address connections you are unfamiliar with.