What’s the Difference Between 127.0.0.0 and 127.0.0.1?

Sometimes the most elementary of questions yield teachable moments; read on as we delve into how a single digit change between 127.0.0.0 to 127.0.0.1 offers a chance to look at network topology.

The Question

What’s the Difference Between 127.0.0.0 and 127.0.0.1?

I know that both are loopback IPs, but they have another ip mask.

What’s the difference between them? Can they be used interchangeably?

===========================================================================

IPv4 routes
===========================================================================
Active routes:
Destination               Mask          Gateway        Interface Metric
      0.0.0.0          0.0.0.0      192.168.1.1      192.168.1.6     26
[...]
    127.0.0.0        255.0.0.0         On-link         127.0.0.1    306
    127.0.0.1  255.255.255.255         On-link         127.0.0.1    306

What kind of information can we tease out from this table?

Interview Questions for Check Point Firewall Technology

Question 1 – Which of the applications in Check Point technology can be used to configure security objects?

Answer:SmartDashboard

Question 2 – Which of the applications in Check Point technology can be used to view who and what the administrator do to the security policy?

Answer:SmartView Tracker

Question 3 – What are the two types of Check Point NG licenses?

Answer:Central and Local licenses

Central licenses are the new licensing model for NG and are bound to the SmartCenter server. Local licenses are the legacy licensing model and are bound to the enforcement module.

Question 4 – What is the main different between cpstop/cpstart and fwstop/fwstart?

Answer:Using cpstop and then cpstart will restart all Check Point components, including the SVN foundation. Using fwstop and then fwstart will only restart VPN-1/FireWall-1.

Question 5 – What are the functions of CPD, FWM, and FWD processes?

Answer:CPD – CPD is a high in the hierarchichal chain and helps to execute many services, such as Secure Internal Communcation (SIC), Licensing and status report.

FWM – The FWM process is responsible for the execution of the database activities of the SmartCenter server. It is; therefore, responsible for Policy installation, Management High Availability (HA) Synchronization, saving the Policy, Database Read/Write action, Log Display, etc.

FWD – The FWD process is responsible for logging. It is executed in relation to logging, Security Servers and communication with OPSEC applications.

Question 6 – What are the types of NAT and how to configure it in Check Point Firewall?

Answer:Static Mode (Manually Defined)

ROUTING - Inetview Questions

ROUTING

Default Administrative distance :
Connected Interface – 0
Static Route - 1
External BGP -20
Internal EIGRP -90
IGRP – 100
OSPF-110
IS-IS- 115
RIP V1, V2-120
External EIGRP-170
IBGP-200
Unknown-255

Distance vector Protocol:
It finds best path by using distance i.e Hops. Ex: RIP, IGRP

Link State Protocol:
Using 3 tables finds best path (Neighbor Table, Topology Table, and Routing Table).( OSPF,IS-IS).
Link state protocols using Area architecture.
The link state Protocol advertise its all routes to neighbor, even though the neighbors not using those routes.

Hybrid Protocol:
Mixing of Distance vector and Link state. (EIGRP).
EIGRP advertise only the best route about its neighbors, to its neighbor. So that only EIGRP is not coming under Link state routing protocol.

ROUTING Preference
1. Specific subnet Mask
2. Administrative difference
3. Metric

EIGRP - Network Interview Questions

EIGRP

I ) EIGRP Features

1. Fast convergence –It is using DUAL (Diffusing update algorithm). Router running Eigrp stores backup route (feasible successor).
2. Minimum Bandwidth usage- It does not make periodic updates (NON PERIODIC). It partial updates when the topology changes and Bounded.
3. Multiple Network layer protocol support- It supports IPX/SPX, Apple talk.
4. It supports VLSM, classless routing.
5. It supports load balancing of equal and unequal cost paths (up to 6 paths. Default is 4)
6. Use multicast (224.0.0.10) instead of broadcast
7. Summarization can do any router running in EIGRP. But in OSPF only in ABR and ASBR.
8. Combines best of distance vector and link state
9. hello packets from any EIGRP - 5 sec, hold-on time is 3 times to hello
10. Hello Packet on NBMA is - 60 sec and hold-on time is 3 times (180 sec)

II) Advertisement distance :Cost between next hop router and destination router.

Feasible Distance : Cost between next hop router and destination router (AD) + Cost between local router and next hop router. Lowest FD is the best path (successor).

Successor: Best route stored in routing table and Topology table.

Feasible successor: Backup route stored in Topology table.To be considered A feasible successor, the AD must be less than the FD of the successor. Because of prevent the loop.

Passive Route: Passive state is a state when the router has identified the successor(s) for the destination.

Active Route: Active state when current successor no longer satisfies the Feasibility Condition.

Neighbor Table: List of directly connected routers.
Topology Table: List of routers learned from each neighbor.
Routing Table: List of best routes.

Neighbor table update the routing information in Topology table and routing table is created taking the best paths form the topology table

EIGRP Packets:

Hello- Establish neighbor relationships ( multicast)
Update- send routing updates
Query-Ask neighbors about routing information.
Reply- Respond to query
Ack- Acknowledge all reliable pocket except Hello pocket.

Note: No auto-summary command prevents to advertisement all interfaces in the router. Also it turns on Classless characteristics of EIGRP.

Metric: Bandwidth, Delay, Reliability ,Loading, MTU

Real (default) Metric : 256* (BW+Delay)
BW= 10^7/BW
Delay= Delay in Micro seconds.


If want to change the other metrics manually use this command.This command is not in Cisco website; Very rarely known and used.

#router eigrp 10
#metric weights (tos) k1 k2 k3 k4 k5
Tos- Type of service. It always 0.

Trouble shooting commands:
Show IP EIGRP topology, Show IP EIGRP neighbor, Show IP EIGRP traffic

Summarization:
#IP summary-address EIGRP 1 172.16.0.0 255.255.255.248

Unequal cost load balancing:

#Variance 2 (2 is multiplier)
#Variance 1 ( equal cost load balancing)

Stuck in Active:A router sends query message for identify the backup route to other routers through its active interfaces. The router will wait for 3minits to get reply messages from all routers even though it gets a backup route from any of one routers.

Methods to Prevent STA : 1) Summary route 2) Stub configuration

NewYork#sh ip eigrp neighbor

IP-EIGRP neighbors for process 10
H Address Interface Hold Uptime SRTT RTO Q Seq
(sec) (ms) Cnt Num
1 172.16.251.2 Se0/1 10 00:17:08 28 2604 0 7
0 172.16.250.2 Se0/0 13 00:24:43 12 2604 0 14.

Router# show ip eigrp topology
IP-EIGRP Topology Table for process 77
Codes: P - Passive, A - Active, U - Update, Q - Query, R - Reply, r - Reply status
P 172.16.90.0 255.255.255.0, 2 successors, FD is 0
via 172.16.80.28 (46251776/46226176), Ethernet0
via 172.16.81.28 (46251776/46226176), Ethernet1
via 172.16.80.31 (46277376/46251776), Serial0
P 172.16.81.0 255.255.255.0, 1 successors, FD is 307200
via Connected, Ethernet1
via 172.16.81.28 (307200/281600), Ethernet1
via 172.16.80.28 (307200/281600), Ethernet0
via 172.16.80.31 (332800/307200), Serial0

Network and Security interview questions (Cisco)

Cisco Firewall


0.What is Stateful Inspection & Packet Filtering.Whats the difference ?
1.What is Adaptive Security Algorithm?
2.what are the default security levels for interfaces in firewall?
2.How would the firewall treat a TCP and UDP packets when it crosses the firewall ?
3.Tell me abt the different types of NAT?
3.What is the order of NAT ?
4.what is NAT Control ?
5.What are the troubleshooting mechanism to be followed in Cisco Firewalls?
a) different flow lookups in the output of Packet Tracer?
6.What is Stateful Failover ? (command to enable failover)
7.what is Transparent Firewall ?
8.how to check the the connections and NAT Translations?
9.How would you trouble shoot the high utilization issue in firewall ?
10.one of the best issues u have troubleshooted with firewall ?
11.Diff between a IPS & Firewall ?


VPN


1.What is Site-Site and Remote Access VPN?
2.What is phase 1 tunnel and the paramters involved ?
3.What is phase 2 tunnel and the paramters involved ?
4.What is PFS ?
5.Why would a DH is required ?
6.How to check the status of the tunnel in phase 1 & 2 ?
7.what are the commands required to troubleshoot VPN?
8.what is GRE and why its required?
9.How can we carry routing updates via IPSEC without GRE?
10.What is NAT Traversal?
11.What are the ports involved in NAT Traversal ?


General


1.Diff between TCP & UDP?
2.What is ARP & RARP?
3.Firewall works at what Layer?
4.What is DNS doctoring?
5.What is proxy & Gratituous ARP?
6.Active & Passive FTP?
7.What is DHCP relay agent ? if DHCP server locates in a different subnet , how would the process works?
8 What is MTU and fragmentation ?
9.What is DoS Attack , Spoofing attack ? how can be Prevented?




Routing


1.What is Subneting and Superneting ?
2.What is Static Route and a Default Route ?
3.What is Classful and Class less Routing
4.what is Dynamic Routing? 


A)OSPF

1.Metric Used for OSPF?
2.What are the Parameters required for OSPF neighbourship?
3.What is NSSA , stubby ,total stubby ?
4.How would the cost of the interfaces is calculated?
5.Commands to view the OSPF neighbour?


B)EIGRP


1.Metric for EIGRP and its AD ?
2.What is stuck in active?
3.How would the un equal load balancing works with EIGRP?
4.diff between EIGRP and OSPF ?
5.Commands to view the eigrp neighbour ?


C)BGP


1.What is IBGP and EBGP ?
2.What is LOcal prefernce and MED?
3.What is BGP synchronization ?
4.what is AD of IBG and EBGP?
5.we have two entries in the routing table , say for an example


192.168.1.0 /24 --> 1.1.1.1
192.168.1.128/25 --->2.2.2.2


what is the next hop to reach 192.168.1.200 ?


6.Why is Redistribution required?
7.How would you filter the routes being Redistributed?


Cisco IPS


1.What is IPS and IDS .Tell me the difference between them ?
2.What are the IPS modules you have worked?
3.What is AIP-SSM?
4.What is Promiscuous and Inline Mode?
5.What is a Signature ?Tell me some signature engines?
6.How would you implement an IPS in a Network?
7.How would you manage IPS?
8.What is False Positive and False Negative?
9.What are the event action involved in Inline Mode?

Networking Question for Core Security

Hi Friends ,

Here i am publishing the networking questions which are asked by       interviewer for Core security peoples .

1)How much you are rating your self in networking out of 10.?

2)Which models of Routers and Switches you handled ?

3)What is RIP , EIGRP , OSPF ?

4)What is Static and Dynamic routing ?

5)Why we create VLANS?

6)How you troubleshoot the vlan problem ?

8)How you make it up down port status to up in switch ?

9)What is access list give the example of both standard and 
extended access list .

10)How you monitor ISP link in router ?

11)How to see the interface status in router and switches ?

12)How to take backup of router and switches configurations?

13)what is difference between SSH and Telnet ?

14)In which layer ICMP works??

15)What is private and public IP shema ?

16)What is span and spanning tree in Switches ?

17)Do you know about MPLS ?

18)What is the latest IOS of your router and swithces ?

19)How you can save the configuration of Routers and Switches ?

20)What is 802.1q ?