It's only discrimination if you thought the person you hired would be better because s/he came from a "better" neighbourhood.
Are you sure about that, extopia?
"The Employment Equality Act, 1998 and the Equal Status Act, 2000 as amended by the Equality Act 2004 (pdf) outlaw discrimination in employment, vocational training, advertising, collective agreements, the provision of goods and services and other opportunities to which the public generally have access. Specifically, service providers, agencies, and anyone providing opportunities to which the public have access, cannot discriminate against citizens on nine distinct grounds.
These grounds are:
gender
marital status
family status
sexual orientation
religion
age (does not apply to a person under 16)
disability
race
membership of the Traveller community."
Which of the 9 grounds applies?
On a general note, there has been too much discussion about discrimination in this thread IMHO. A question can be offensive, rude, even stupid but it is never discriminatory. For legal discrimination to apply an action must have been taken such as a job refusal, promotion refusal etc based on one or other of the above-mentioned grounds and must be agreed to be so by the Authority.
An employer is of course recommended to avoid asking questions of a nature which could in the event of a job being refused etc support the complainant's assertion that the act may have been discriminatory. It doesn't in itself mean that the claim will be upheld however.
Anyone with any real experience of interviewing prospective employees will know just how difficult the process is and appreciate that even the best of interviewers will occasionally get it wrong with possible dire consequences for both sides. Whereas it's easy to check claimed qualifications, it can be very difficult to determine just what type of person the candidate is. Dependent on the job it's often vital to determine how will he (meaning 'he' or 'she'!) fit in? Will he be a good person to work with and if relevant be good with clients or customers? Is he serious about the job and interested in making a career of it? Self-confident? Self-reliant? Promotion material? Likely to be able to manage staff? The list goes on.
There is no magic formula for determining such factors. References are often not worth the paper they are written on, leaving the interviewer little choice but to try to get the candidate to open up and talk about himself. Appearance, presentation, general lifestyle, interests, etc can all provide clues.
It's as much in the candidate's interest to know that he is the type of person they want so why be defensive about being asked whether he is married or not, or be uptight because an interviewer pays him a compliment? Ironically it's often possible to spot someone who is being defensive so I'd say go in with a positive attitude. What have you got to lose? If you are right for the job you won't be refused it. If you are not, so what? Worry about discrimination if and only if it ever arises. If you don't like the line of questioning then maybe you are learning something about the employer and that's something you take into consideration to help you decide if you want to work there anyway.