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   Side A Side B      Side A Side B 1. IMAP Interactive Mail Access Protocol, Version...   10. SNMP Simple Network Management ProtocolPort 161TCP,... 2. SFTP Simple File Transfer ProtocolPort 115TCP   11. POP3 Post Office Protocol 3Port 110TCP 3. TFTP Trivial File Transfer ProtocolPort 69UDP   12. HTTP HyperText Transfer ProtocolPort 80TCP 4. BOOTP Client Bootstrap Protocol ClientPort 68UDP   13. BOOTP Server Bootstrap Protocol ServerPort 67UDP 5. Graphics Port 41TCP, UDP   14. DNS Domain Name SystemPort 53TCP, UDP 6. SMTP Simple Mail Transfer ProtocolPort 25TCP   15. RIP Routing Information ProtocolPort 520UDP 7. Telnet Protocol Used for remote accessPort 23TCP   16. FTP Server File Transfer ProtocolPort 21TCP 8. FTP Client File Transfer ProtocolPort 20TCP   17. RTSP Real Time Streaming ProtocolPort 554TCP,... 9. DHCP Client Dynamic Host Configuration Protocol ClientPort...   18. DHCP Host Dynamic Host Configuration Protocol Jost Port...

IP Spoofing is a technique used to gain unauthorized access to machines, whereby an attacker illicitly impersonate another machine by manipulating IP packets. IP Spoofing involves modifying the packet header with a forged (spoofed) source IP address, a checksum, and the order value. Internet is a packet switched network, which causes the packets leaving one machine may be arriving at the destination machine in different order. The receiving machine resembles the message based on the order value embedded in the IP header. IP spoofing involves solving the algorithm that is used to select the order sent values, and to modify them correctly.

SYSVOL is the acronym for the SYSFOL folder and all of the files stored in it on the Windows Operating System (OS). It stores the server’s copy of public data and files for the domain. These files consist of group or user policy information. The information stored in the SYSVOL folder is copied to all domain controllers on the respective domain. What are the SYSVOL Requirements? First, the SYSVOL folder has to be located on a Windows NTFS volume. The information stored in the SYSVOL folder is replicated on all domain controllers’ local disk via the File Replication Service (FRS), which must be installed for the operation to work properly. For network clients to access the SYSVOL tree’s contents, they must gain permission to access the NETLOGON and SYSVOL folders. The SYSVOL folder is used for a number of common networking applications, including adding a domain to an existing set or “Forest” of domain servers and locally creating a new logon script. How to Add a Domain to an

Hedrick of Rutgers University invented the Routing Information Protocol in the summer of 1988. Since then it has become the most common routing protocol on LANs and WANs and continues to be used today. Hedrick’s work was based on the Unix computer program “routed,” which was distributed with the 4.3 version of the BSD branch of the OS. At that time, the “routed” protocol was the de-facto standard for research laboratories to communicate via network gateways. The RIP protocols use the Bellman-Ford algorithm for distance vector computation and other work completed as early as 1969 on the ARPANET. The PUP protocol preceded Hedrick’s work and later became the RIP. How does the Routing Information Protocol Work? RIP relies on a routing database that stores information on the fastest routes that exist between destinations on the network. This lets each router tell others the fastest route(s) and uses an update algorithm that revises route updates for each router based on the latest info

The Routing Information Protocol (RIP) is the IGP standard protocol that is used on Local Area Networks (LANs). It helps to ensure a higher degree of network stability by quickly re-routing network packets if one of the network connections goes offline. When the RIP is active on a network, users experience little to no service interruptions due to single router, switch, or server outages if there are sufficient network resources available to continue routing network traffic.

An RPC server may be unavailable for a number of reasons. If the service that a client is attempting to contact no longer exists or has been moved to a different location, the RPC server will appear unavailable because it cannot fulfill the client’s request. Another reason an RPC server may be unavailable is that the network is experiencing hardware or software-related difficulties that must be repaired before the RPC server can be contacted. Likewise, a user may have disabled the RPC server or specifically prevented remote clients from contacting it. How to Fix RPC Server In order to fix an RPC server, the user must identify the problem that is causing the RPC server to be unavailable in the first place. The user should check all network cables, restart all network devices, and, if possible, manually check the RPC server for malfunctions and accessibility restrictions.

RPC implements a series of tasks in order to establish communication between a client and a server. First, the client initiates a specific objective by contacting a local process known as a “client stub” with parameters for accessing a file or service. The client stub converts the parameters it receives from the client into appropriate parameters on the server. The client stub then sends these new parameters to the operating system’s kernel, which then sends the message to the server stub (same as client stub, but is located on the server machine). The server stub decodes the message and sends it to the appropriate application or service. Once the application has been contacted, replies may be sent in the reverse direction through each of these processes.

An MPLS (Multi-Protocol Label Switching) network is one in which many devices are connected to each other through a master system that receives data from each individual device and relays it to any other device within the network. MPLS networks differ from traditional networks because they connect a large number of devices across long distances by tunneling through the Internet. How MPLS Networks Work An MPLS network is a cloud-like system of computers and other devices that all communicate with each other by assigning labels to data packets so that they can be forwarded from one device to another. For example, if Device A wishes to send a data packet to Device E, Device A will insert a header in the data packet with a label stack that contains information about the data packet, where it came from, and where it is going. Device A will then send the data packet to Device B, Device B will send the data packet to Device C, Device C will send the data packet to Device D, and Device D

A VPLS (Virtual Private LAN Service) is a network protocol that allows users to connect many different ethernet-based local area networks together over long distances. VPLS uses MPLS data packets and the Internet in order to forward information from one or more computers in one network to one or more computers in another network and then expand that to include even further networks that are all connected via the VPLS. Businesses and government agencies that have branches in many different locations generally use VPLS systems. However VPLS systems can also be used for gaming and other purposes that require networks to send and receive data outside of each network’s physical operation range. How VPLS Works VPLS networks work in similar to both LAN and MPLS networks. In a VPLS system, data is arranged in packets and labeled according to what it is, where it came from, and where it is going. Each packet is then sent to the nearest computer within the network in alphabetical order. As

The Hot Standby Router Prtocol (HSRP) is a networking protocol that supports the non-disruptive failover of Internet Protocol (IP) traffic in special circumstances. HSRP also allows network hosts to look like they are using a single router and keep connected if the first hop router being used fails to respond. The protocol guards against the failure of the first hop router in a network infrastructure when the router’s IP address cannot be found dynamically. The HSRP normally joins several routers together to create a single virtual server that client machines and networks use. The protocol helps to ensure that only one of the virtual server’s routers is working at any given time. How does the Hot Standby Router Protocol Work? The router that forwards packets for the virtual router is referred to as the active router. There is also a designated standby router in the scheme in the event that the primary router fails. The protocol makes router assignments based on the IP address assi

A VPN (Virtual Private Network) server is one that is connected to a Virtual Private Network in order to allow remote users to access files on the server. Companies, government agencies, and various institutions use VPN servers in order to provide users who are away from the server with consistent access to important files and software. Likewise, VPN servers are used domestically to ensure that users have access to computer files while they are away from their home or office. How VPN Servers Work A VPN server is simply one that is connected to a Virtual Private Network. A Virtual Private Network (VPN) channels through the Internet in order to connect a multitude of users, servers, and devices together. VPNs can also include other networks, such as local area networks, and are encrypted to ensure that only users who have the proper authorization can access them. VPN networks are dependent on both a server and client. The server hosts the main files and the client is all other devic

The Simple Network Time Protocol (SNTP) is a simpler version of the Network Time Protocol (NTP). SNTP synchronizes the time between networked computer systems and is relied on when data is being transferred via the Internet. The NTP protocol is one of the most established protocols still used on the Internet. It uses a GPS or radio clock to tell time and is accurate past the seconds place. Why is the SNTP Necessary? The need for precise time synchronization has continued to increase with the evolution of computer technology over the past several decades. In the networking field, network servers and their client computers require precision to the millisecond and beyond in order to ensure data file transfers occur without errors. Computers also require specific time synchronization in order to ensure data packet and email delivery in the proper sequence to destination networks and email recipients. The importance of the SNTP and NTP protocols exponentially expands with the number of

The Virtual Switch What really sets Hyper-V apart from Microsoft’s other virtualization products is that virtual machines perform much better because they can communicate with the server’s hardware directly rather than having to pass hardware requests through the host operating system (although there are some exceptions to this). Of course you can’t just bombard a network adapter with simultaneous traffic from multiple virtual machines. There has to be a way of managing the traffic. To get around this problem, Microsoft has introduced the concept of the virtual switch. To understand how this is possible, you have to realize that Hyper-V is not a Windows Server 2008 add-on, but rather is a part of the operating system. When you install the Hyper-V role, the hyper visor is placed “underneath” the Windows 2008 operating system. The existing operating system (known as the host operating system) is placed into something called the parent partition, and each guest operating sys

Is your network cable plugged in? (physical) Is there a link light on the Ethernet switch and Ethernet NIC? (data-link) Do you have an IP address? (network) Can you ping your default gateway? (network, testing LAN IP connectivity) Do you have DNS server information? Can you ping your DNS server? (network, testing IP connectivity) Do you have a firewall configured? (network on up to application) Can you ping the host you are trying to get to by name? (application, DNS and network WAN IP connectivity) What format is the graphic in? Do you have a viewer for that format? (presentation) Can your web browser open up another website? (basic application troubleshooting) It may turn out that the graphic they were trying to bring up was a .TIFF file and they didn’t have a decoder for that type of file. Thus, this would have been a presentation error issue as the presentation layer deals with formats of graphics & files, as well as compression and encryption.

The Open System Interconnection Reference Model (OSI) is a seven layer model that was developed as part of the effort to standardize networking that was started in the late 1970's as part of the Open Systems Interconnection (OSI) initiative. The Seven Layers of the OSI Model The Physical Layer defines the electrical and physical properties and the operating specifications for the devices and media in use. The main job of the Physical Layer is the physical "connection" or attachment of given media and how it is configured (e.g. Token Ring cable, size of cable used, termination in place etc.). In some instances, there may be secondary responsibilities of this layer depending on the device for things such as flow control, modulation/demodulation and so forth. The protocol data unit in use at this level of the OSI model is referred to as a "bit." The Data Link Layer provides the practical means to transfer data between network nodes as its main job is to transfe

The first, and probably most important step, is to put down this row of values: 128 64 32 16 8 4 2 1 In order to remember these values start with the number 1, go from right to left, and double that number seven times. For example, start with 1 on the right side. For your next number, double the 1 (1 x 2 = 2). So, 2 is your next number (remembering to go from right to left). For your third number, double the 2 (2 x 2 = 4); to continue the sequence, double the 4 (4 x 2 = 8). Repeat this process until you’ve doubled your original number, seven times. The key to this is that every single one of the values we put in that row are going to have either number 1 or number 0 assigned to it. To convert the IP address we will take that string of numbers and start from left to right this time. For each value we ask this question: “Can I subtract this value from the decimal remaining?” If the answer is “NO” then you put a “0” under the binary value, and if the answer is “Y

ODR is used to allow hub routers to accept prefix information, distributed via Cisco Discovery Protocol (CDP) , from spoke routers. On the hub router, enter this command router odr Also, routes can be controlled with a distribute-list: distribute-list 10 in distribute-list 20 out assuming the referenced ACLs exist, otheriwse no routes are accepted or sent. Since the prefix updates are carried on CDP, ODR updates can be controlled, in true sledgehammer fashion, by disabling CDP on an interface:interface serial 0/0 no cdp enable For ODR to work properly, all dynamic routing protocols need to be disabled on the spoke routers.

IGRP is a proprietary routing protocol designed by Cisco and can only be used in a homogeneous network of Cisco routers. IGRP is a distance-vector protocol that considers delay, bandwidth and other optional parameters to determine the best path. IGRP uses an autonomous system number parameter in the configuration. All routers with the same autonomous system number will share router advertisements and participate. This number is arbitrary but must be the same on all routers within the autonomous system. To configure a router to participate in IGRP routing within autonomous system 5 and advertise routing information about the 192.168.200.0 network, use: conf t router igrp 5 network 192.168.200.0

Using a Cisco router as a DHCP server can simplify a network configuration by cetralizing DHCP services in a large network or decentralizing DHCP services to the endpoint routers at satellite locations. The ease of remote management of Cisco-based DHCP services is a great advantage. conf t service dhcp ip dhcp pool 192.168.1.0/24 network 192.168.1.0 255.255.255.0 default-router 192.168.1.1 dns-server 192.168.1.5 192.168.1.6 exit ip dhcp excluded-address 192.168.1.1 192.168.1.199 ip dhcp excluded-address 192.168.1.241 192.168.1.255 ^Z This example shows a Cisco router configuration as a basic DHCP server in the 192.168.1.0/24 network. The DHCP options implemented are default-router (DHCP option 3) and dns-server (DHCP option 6). Two DNS servers are configured. With the excluded-address commands, using only ip addresses between 192.168.1.200-192.168.1.240 will be available for client use.

HSRP stands for Hot Standby Router Protocol, and what it does is create a virtual IP address (which hosts will use as the gateway address). This virtual address is free to move between configured routers as needed. Some background for this config: Local Subnet: 192.168.2.0/24 Desired gateway address: 192.168.2.1 Both routers and their hosts must be on the same layer 2 network. On Router A: ip address 192.168.2.2 255.255.255.0 standby 1 ip 192.168.2.1 standby 1 preempt standby 1 priority 110 standby 1 authentication myrouter standby 1 track serial 0/0 The priority number determines which router will normally have the virtual IP address, higher numbers win. The track statement tells the router to give up the virtual address if the serial 0/0 interface goes down. Router B: ip address 192.168.2.3 255.255.255.0 standby 1 ip 192.168.2.1 standby 1 preempt standby 1 priority 100 standby 1 authentication myrouter standby 1 track serial 0/1 That’s all there is