TCP is a connection-oriented protocol. When a session from a more secure host inside the security appliance is started, the security appliance creates an entry in the session state filter. The security appliance is able to extract network sessions from the network flow and actively verify their validity in real time.
When a TCP session is established over the security appliance, the following happens:
Step 1 The first IP packet from an inside host causes the generation of a translation slot. The embedded TCP information is then used to create a connection slot in the security appliance.
Step 2 The connection slot is marked as embryonic (not established yet).
Step 3 The security appliance randomizes the initial sequence number of the connection, stores the delta value, and forwards the packet onto the outgoing interface. The security appliance now expects a synchronization-acknowledgment (SYN-ACK) packet from the destination host. Then the security appliance matches the received packet against the connection slot, computes the sequencing information, and forwards the return packet to the inside host.

Step 4 The inside host completes the connection setup, the three-way handshake, with an ACK.
Step 5 The connection slot on the security appliance is marked as connected, or activeestablished, and data is transmitted. The embryonic counter is then reset for this connection.

Which statements are true regarding ISDN channels? (Select three)
A. Each B channel can transmit up to 64 kbps
B. The ISDN B channel carries voice or data
C. The ISDN D channel transmits control information.
D. The D channel transmission rate varies depending on the service used.
E. HDLC or PPP can be used to encapsulate D channel information.
Answer: A, B, C
Explanation:
Integrated Services Digital Network (ISDN) is essentially digital telephone service.  ISDN envisions telephone  companies providing “Integrated Services,” capable of handling voice, data, and video over the same circuits.
The two primary variants of ISDN are BRI (Basic Rate Interface) and PRI (Primary Rate Interface). BRI, sometimes referred to as 2B+D, provides two 64 kbps B channels and a 16 kbps D channel over a single 192 kbps circuit (the remaining bandwidth is used for framing). The D channel is used for control information. BRI is the ISDN equivalent of a single phone line, though it can handle two calls simultaneously over its two B channels. PRI, essentially ISDN over T1, is referred to as 23B+D and provides 23 B channels and a 64 kbps D channel. PRI is intended for use by an Internet Service Provider, for example, multiplexing almost two dozen calls over a single pair of wires.

The Frame Relay circuit between Mexico and Canada is experiencing congestion. Which types of notification are used to alleviate the congestion? (Choose three.)
A. FECN
B. CIR
C. BECN
D. DE
E. DLCI 100 is down
F. DLCI 200 is down
Answer: A, C, D
Explanation:
In a frame relay network, FECN (forward explicit congestion notification) is a header bit transmitted by the source (sending) terminal requesting that the destination (receiving) terminal slow down its requests for data. BECN (backward explicit congestion notification) is a header bit transmitted by the destination terminal requesting that the source terminal send data more slowly. FECN and BECN are intended to minimize the possibility that packets will be discarded (and thus have to be resent) when more packets arrive than can be handled.
If the source terminal in a communications circuit generates frequent FECN bits, it indicates that the available network bandwidth (at that time) is not as great as can be supported by the destination terminal. Likewise, if the destination generates frequent BECN bits, it means the available network bandwidth (at that time) is not as great as can
be supported by the source. In either case, the root cause is lack of available bandwidth at the times during which FECN or BECN bits are generated. This can occur because of outdated or inadequate network infrastructure, heavy network traffic, high levels of line noise, or portions of the system going down. Identifying and resolving these issues can improve overall network performance, especially when the system is called upon to carry a large volume of traffic.
Discard Eligibility (DE) When there is congestion on the line, the network must decide which frames to discard in order to free the line. Discard Eligibility provides the network with a signal to determine which frames to discard. The network will discard frames with a DE value of 1 before discarding other frames. The DE bit may be set by the user on some of its lower-priority frames. Alternatively, the network may set the DE bit to indicate to other nodes that a frame should be preferentially selected for discard, if necessary.

Which PPP sub-protocol negotiates authentication options?

A. NCP
B. ISDN
C. SLIP
D. LCP
E. DLCI

Answer: D
Explanation:
PPP defines the Link Control Protocol (LCP). The job of the LCP is to establish,  configure, and test the data-link connection. When hosts negotiate a PPP connection, they  exchange LCP packets. These packets allow link partners to dynamically negotiate link options, including authentication, compression, and MLP. The protocol field is used to
identify various Layer 3 protocols, such as IP or IPX. The LCP field allows for the following features:
1. Authentication
2. Callback
3. Compression
4. Multilink PPP
Once the LCP establishes the Layer 2 connection, the Network Control Protocol (NCP) takes over. Link partners exchange NCP packets to establish and configure different network-layer protocols including IP, IPX, and AppleTalk. Each Layer 3 protocol has its own NCP. For example, IP’s NCP is IPCP. IPX’s NCP is IPXCP and Appletalk’s NCP is
ATALKCP.

With the use of leased lines, a company currently connects to its five remote branch offices. Which alternative could be used to provide connection-oriented, high performance, packet-switched connectivity?
A. PPP
B. DSL
C. ISDN
D. Frame Relay
E. POTS
Answer: D
Explanation:
Frame Relay uses statistical multiplexing techniques to provide network access in a packet-switched network. There are three packet switching technologies which can be
used:
1. Frame Relay
2. X.25
3. ATM
ISDN also contains some packet switching techniques, but only frame relay is connection oriented. Frame relay also offers higher speed options.

Which of the following are options for Frame Relay LMI types on Cisco routers?
(Choose three)

A. Cisco
B. IEEE
C. Q933a
D. ANSI
E. IETF
F. Q.931
Answer: A, C, D
Explanation:
Setting the LMI Type:
If the router or access server is attached to a public data network (PDN), the LMI type  must match the type used on the public network. Otherwise, the LMI type can be set to suit the needs of your private Frame Relay network.
You can set one of three types of LMIs on our devices:

frame-relay lmi-type {ansi | cisco | q933a}

What is the function of the command switchport trunk native vlan 150 on the Cisco Catalyst Switch?
A. It creates a VLAN 150 interface
B. It designates VLAN 150 for untagged traffic
C. It blocks VLAN 150 traffic from passing on the trunk
D. It designates VLAN 150 as the default for all unknown tagged traffic.
Answer: B
Explanation:
In 802.1Q trunking, all VLAN packets are tagged on the trunk link to indicate the VLAN to which they belong. Frames belonging to the Native VLAN are sent untagged on the trunk link. The Native VLAN contains ports not assigned to other VLANs that by default belong to VLAN 1. VLAN 1 is the Native VLAN by default, but VLANs other than VLAN 1 may be designated as the Native VLAN. However, the Native VLAN must be the same on trunked switches in 802.1Q trunking. If a VLAN other than VLAN 1 is to be the Native VLAN, it needs to be identified on the trunk ports. In the interface configuration mode of the trunk port(s), the IOS-based command to designate the Native VLAN is switchporttrunk native.
Switch(config-if)#switchport trunk native vlan vlan-id
The switchporttrunk native vlan command is only necessary when changing the native VLAN from something other than VLAN 1 or changing it back to VLAN 1.

BGP is an extremely complex protocol used throughout the Internet and within multinational organizations. Its main purpose is to connect very large networks or autonomous systems.
In many cases, the routing policy that is implemented in an AS is consistent with the policy for the ISP. In these cases, it is not necessary or even desirable, to use BGP to exchange routing information with the ISP. Instead, connectivity can be achieved through a combination of static routes and default routes.
Do not use BGP within the AS in the following situations:
1. There is only a single connection to the Internet or other AS.
2. Internet routing policy and route selection are not of concern to the AS.
3. The BGP routers have insufficient RAM or processor power to handle constant updates.
4. There is limited understanding of route filtering and the BGP path selection process.
5. Low bandwidth link between autonomous systems

The term encapsulation describes the process of putting headers and trailers around some data. A computer that needs to send data encapsulates the data in headers of the correct format so that the receiving computer will know how to interpret the received data. Data encapsulation with TCP/IP consists of five-steps:

Step 1: Create the application data and headers.

Step 2: Package the data for transport, which is performed by the transport layer (TCP or UDP). The Transport Layer creates the transport header and places the data behind it.

Step 3: Add the destination and source network layer addresses to the data, which is performed by the Inter network Layer. The Internetwork Layer creates the network header, which includes the network layer addresses, and places the data behind it.

Step 4: Add the destination and source data link layer addresses to the data, which is performed by the Network Interface Layer. The Network Interface Layer creates the data link header, places the data
behind it, and places the data link trailer at the end.

Step 5: Transmit the bits, which is performed by the Network Interface Layer. The Network Interface Layer encodes a signal onto the medium to transmit the frame.